21297907161 has 12 divisors (see below), whose sum is σ = 30765414420. Its totient is φ = 14197787520.

The previous prime is 21297907129. The next prime is 21297907187. The reversal of 21297907161 is 16170979212.

It can be written as a sum of positive squares in 2 ways, for example, as 20070105561 + 1227801600 = 141669^2 + 35040^2 .

It is not a de Polignac number, because 21297907161 - 2⁵ = 21297907129 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21297909161) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 126085 + ... + 241853.

It is an arithmetic number, because the mean of its divisors is an integer number (2563784535).

Almost surely, 2^21297907161 is an apocalyptic number.

It is an amenable number.

21297907161 is a deficient number, since it is larger than the sum of its proper divisors (9467507259).

21297907161 is a wasteful number, since it uses less digits than its factorization.

21297907161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 136216 (or 136213 counting only the distinct ones).

The product of its (nonzero) digits is 95256, while the sum is 45.

The spelling of 21297907161 in words is "twenty-one billion, two hundred ninety-seven million, nine hundred seven thousand, one hundred sixty-one".