129557231 has 4 divisors (see below), whose sum is σ = 129600312. Its totient is φ = 129514152.

The previous prime is 129557227. The next prime is 129557243. The reversal of 129557231 is 132755921.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 129557231 - 2² = 129557227 is a prime.

It is a super-2 number, since 2×129557231² = 33570152208774722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 129557191 and 129557200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (129557531) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16661 + ... + 23166.

It is an arithmetic number, because the mean of its divisors is an integer number (32400078).

Almost surely, 2^129557231 is an apocalyptic number.

129557231 is a deficient number, since it is larger than the sum of its proper divisors (43081).

129557231 is an equidigital number, since it uses as much as digits as its factorization.

129557231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43080.

The product of its digits is 18900, while the sum is 35.

The square root of 129557231 is about 11382.3209847553. The cubic root of 129557231 is about 506.0039251988.

The spelling of 129557231 in words is "one hundred twenty-nine million, five hundred fifty-seven thousand, two hundred thirty-one".