129221568 has 168 divisors, whose sum is σ = 439350912. Its totient is φ = 36889344.

The previous prime is 129221537. The next prime is 129221581. The reversal of 129221568 is 865122921.

129221568 is a `hidden beast` number, since 1 + 2 + 92 + 2 + 1 + 568 = 666.

It is a tau number, because it is divible by the number of its divisors (168).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 108271 + ... + 109457.

It is an arithmetic number, because the mean of its divisors is an integer number (2615184).

Almost surely, 2^129221568 is an apocalyptic number.

129221568 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 129221568, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (219675456).

129221568 is an abundant number, since it is smaller than the sum of its proper divisors (310129344).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

129221568 is an equidigital number, since it uses as much as digits as its factorization.

129221568 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1221 (or 1199 counting only the distinct ones).

The product of its digits is 17280, while the sum is 36.

The square root of 129221568 is about 11367.5664941974. The cubic root of 129221568 is about 505.5665542956.

The spelling of 129221568 in words is "one hundred twenty-nine million, two hundred twenty-one thousand, five hundred sixty-eight".