129157921 has 2 divisors, whose sum is σ = 129157922. Its totient is φ = 129157920.

The previous prime is 129157883. The next prime is 129157961. The reversal of 129157921 is 129751921.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 127803025 + 1354896 = 11305^2 + 1164^2 .

It is a cyclic number.

It is not a de Polignac number, because 129157921 - 2⁹ = 129157409 is a prime.

It is not a weakly prime, because it can be changed into another prime (129157961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64578960 + 64578961.

It is an arithmetic number, because the mean of its divisors is an integer number (64578961).

Almost surely, 2^129157921 is an apocalyptic number.

It is an amenable number.

129157921 is a deficient number, since it is larger than the sum of its proper divisors (1).

129157921 is an equidigital number, since it uses as much as digits as its factorization.

129157921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 11340, while the sum is 37.

The square root of 129157921 is about 11364.7666496061. The cubic root of 129157921 is about 505.4835364749.

The spelling of 129157921 in words is "one hundred twenty-nine million, one hundred fifty-seven thousand, nine hundred twenty-one".