129979685921 has 2 divisors, whose sum is σ = 129979685922. Its totient is φ = 129979685920.

The previous prime is 129979685917. The next prime is 129979685929. The reversal of 129979685921 is 129586979921.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 65443872400 + 64535813521 = 255820^2 + 254039^2 .

It is a cyclic number.

It is not a de Polignac number, because 129979685921 - 2² = 129979685917 is a prime.

It is not a weakly prime, because it can be changed into another prime (129979685929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64989842960 + 64989842961.

It is an arithmetic number, because the mean of its divisors is an integer number (64989842961).

Almost surely, 2^129979685921 is an apocalyptic number.

It is an amenable number.

129979685921 is a deficient number, since it is larger than the sum of its proper divisors (1).

129979685921 is an equidigital number, since it uses as much as digits as its factorization.

129979685921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 44089920, while the sum is 68.

The spelling of 129979685921 in words is "one hundred twenty-nine billion, nine hundred seventy-nine million, six hundred eighty-five thousand, nine hundred twenty-one".