def b64_encode(decimal):
    char_lower = 'abcdefghijklmnopqrstuvwxyz'
    char_upper = char_lower.upper()
    char_num = '0123456789'
    char_special = '=/'
    char_b64 = char_upper+char_lower+char_num+char_special
    char_b64 = list(char_b64)
    val = decimal
    val_mod = []
    val_return = []
    if val <= 64:
        return char_b64[val % 64]
    else:
        while val > 64:
            val_mod.append(val % 64)
            val = int(val / 64)
            if val < 64:
                val_mod.append(val)
    for i in reversed(val_mod):
        val_return.append(char_b64[i])
    return ''.join(val_return)