21725502165 has 12 divisors (see below), whose sum is σ = 37657537164. Its totient is φ = 11586934464.

The previous prime is 21725502133. The next prime is 21725502167. The reversal of 21725502165 is 56120552712.

21725502165 is a `hidden beast` number, since 21 + 7 + 2 + 550 + 21 + 65 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 6858821124 + 14866681041 = 82818^2 + 121929^2 .

It is not a de Polignac number, because 21725502165 - 2⁵ = 21725502133 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21725502167) 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, 241394424 + ... + 241394513.

It is an arithmetic number, because the mean of its divisors is an integer number (3138128097).

Almost surely, 2^21725502165 is an apocalyptic number.

It is an amenable number.

21725502165 is a deficient number, since it is larger than the sum of its proper divisors (15932034999).

21725502165 is a wasteful number, since it uses less digits than its factorization.

21725502165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 482788948 (or 482788945 counting only the distinct ones).

The product of its (nonzero) digits is 42000, while the sum is 36.

The spelling of 21725502165 in words is "twenty-one billion, seven hundred twenty-five million, five hundred two thousand, one hundred sixty-five".