129421921857 has 16 divisors (see below), whose sum is σ = 175072739520. Its totient is φ = 85035255552.

The previous prime is 129421921831. The next prime is 129421921861. The reversal of 129421921857 is 758129124921.

It is a happy number.

It is not a de Polignac number, because 129421921857 - 2¹⁵ = 129421889089 is a prime.

It is not an unprimeable number, because it can be changed into a prime (129421921457) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1075588 + ... + 1189845.

It is an arithmetic number, because the mean of its divisors is an integer number (10942046220).

Almost surely, 2^129421921857 is an apocalyptic number.

It is an amenable number.

129421921857 is a deficient number, since it is larger than the sum of its proper divisors (45650817663).

129421921857 is a wasteful number, since it uses less digits than its factorization.

129421921857 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2265712.

The product of its digits is 725760, while the sum is 51.

The spelling of 129421921857 in words is "one hundred twenty-nine billion, four hundred twenty-one million, nine hundred twenty-one thousand, eight hundred fifty-seven".