21965801265 has 64 divisors (see below), whose sum is σ = 39457152000. Its totient is φ = 11593642752.

The previous prime is 21965801261. The next prime is 21965801279. The reversal of 21965801265 is 56210856912.

21965801265 is a `hidden beast` number, since 2 + 1 + 9 + 6 + 580 + 1 + 2 + 65 = 666.

It is not a de Polignac number, because 21965801265 - 2² = 21965801261 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21965801265.

It is not an unprimeable number, because it can be changed into a prime (21965801261) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 5891832 + ... + 5895558.

It is an arithmetic number, because the mean of its divisors is an integer number (616518000).

Almost surely, 2^21965801265 is an apocalyptic number.

It is an amenable number.

21965801265 is a deficient number, since it is larger than the sum of its proper divisors (17491350735).

21965801265 is a wasteful number, since it uses less digits than its factorization.

21965801265 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4183 (or 4177 counting only the distinct ones).

The product of its (nonzero) digits is 259200, while the sum is 45.

The spelling of 21965801265 in words is "twenty-one billion, nine hundred sixty-five million, eight hundred one thousand, two hundred sixty-five".