year = 31536000
month = 2592000
week = 604800
day = 86400
hour = 3600


from math import floor


def parse_time(time_s):
    if time_s == 0:
        return None
    if time_s < hour:
        return 'меньше часа'
    if time_s >= year:
        return '{} г. '.format(floor(time_s / year)) + parse_time(time_s % year)
    if time_s >= month:
        return '{} мес. '.format(floor(time_s / month)) + parse_time(time_s % month)
    elif time_s >= week:
        return '{} нед. '.format(floor(time_s / week)) + parse_time(time_s % week)
    elif time_s >= day:
        return '{} д. '.format(floor(time_s / day)) + parse_time(time_s % day)
    else:
        return '{} ч.'.format(floor(time_s / hour))

print(parse_time(2827567.5759670734))  # 1 мес. 2 д. 17 ч.
print(parse_time(269649.6857390404))   # 3 д. 2 ч.

def parse_time(time_s):
    year = 31536000
    month = 2592000
    week = 604800
    day = 86400
    hour = 3600

    if time_s == 0:
        return None

    if time_s < hour:
        return 'меньше часа'

    result = ''

    if time_s >= year:
        result += '{} г. '.format(int(time_s / year))
        time_s %= year

    if time_s >= month:
        result += '{} мес. '.format(int(time_s / month))
        time_s %= month

    if time_s >= week:
        result += '{} нед. '.format(int(time_s / week))
        time_s %= week

    if time_s >= day:
        result += '{} д. '.format(int(time_s / day))
        time_s %= day

    if time_s >= hour:
        result += '{} ч.'.format(int(time_s / hour))

    return result

def parse_time(time_s):
    items = [
        (31536000, '{} г. '),
        (2592000, '{} мес. '),
        (604800, '{} нед. '),
        (86400, '{} д. '),
        (3600, '{} ч.'),
    ]

    if time_s == 0:
        return None

    if time_s < 3600:
        return 'меньше часа'

    result = ''

    for value, fmt in items:
        if time_s >= value:
            result += fmt.format(int(time_s / value))
            time_s %= value

    return result

print(parse_time(2827567.5759670734))  # 1 мес. 2 д. 17 ч.
assert parse_time(2827567.5759670734) == "1 мес. 2 д. 17 ч."

print(parse_time(269649.6857390404))   # 3 д. 2 ч.
assert parse_time(269649.6857390404) == "3 д. 2 ч."