129857940921 has 4 divisors (see below), whose sum is σ = 173143921232. Its totient is φ = 86571960612.

The previous prime is 129857940833. The next prime is 129857940977. The reversal of 129857940921 is 129049758921.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 129857940921 - 2¹⁸ = 129857678777 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (129857948921) 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, 21642990151 + ... + 21642990156.

It is an arithmetic number, because the mean of its divisors is an integer number (43285980308).

Almost surely, 2^129857940921 is an apocalyptic number.

It is an amenable number.

129857940921 is a deficient number, since it is larger than the sum of its proper divisors (43285980311).

129857940921 is an equidigital number, since it uses as much as digits as its factorization.

129857940921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43285980310.

The product of its (nonzero) digits is 3265920, while the sum is 57.

The spelling of 129857940921 in words is "one hundred twenty-nine billion, eight hundred fifty-seven million, nine hundred forty thousand, nine hundred twenty-one".