129931921 has 8 divisors (see below), whose sum is σ = 148789440. Its totient is φ = 111148368.

The previous prime is 129931913. The next prime is 129931933. The reversal of 129931921 is 129139921.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 129931921 - 2³ = 129931913 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (129931951) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14671 + ... + 21796.

It is an arithmetic number, because the mean of its divisors is an integer number (18598680).

Almost surely, 2^129931921 is an apocalyptic number.

It is an amenable number.

129931921 is a deficient number, since it is larger than the sum of its proper divisors (18857519).

129931921 is an equidigital number, since it uses as much as digits as its factorization.

129931921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36983.

The product of its digits is 8748, while the sum is 37.

The square root of 129931921 is about 11398.7683983841. The cubic root of 129931921 is about 506.4912571371.

The spelling of 129931921 in words is "one hundred twenty-nine million, nine hundred thirty-one thousand, nine hundred twenty-one".