21913261965 has 64 divisors (see below), whose sum is σ = 44620485120. Its totient is φ = 9995374080.

The previous prime is 21913261957. The next prime is 21913261991. The reversal of 21913261965 is 56916231912.

21913261965 is a `hidden beast` number, since 2 + 19 + 13 + 2 + 619 + 6 + 5 = 666.

It is not a de Polignac number, because 21913261965 - 2³ = 21913261957 is a prime.

It is a super-2 number, since 2×21913261965² (a number of 21 digits) contains 22 as substring.

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 21913261965.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 406495 + ... + 457235.

It is an arithmetic number, because the mean of its divisors is an integer number (697195080).

Almost surely, 2^21913261965 is an apocalyptic number.

It is an amenable number.

21913261965 is an abundant number, since it is smaller than the sum of its proper divisors (22707223155).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21913261965 is a wasteful number, since it uses less digits than its factorization.

21913261965 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51219 (or 51213 counting only the distinct ones).

The product of its digits is 174960, while the sum is 45.

The spelling of 21913261965 in words is "twenty-one billion, nine hundred thirteen million, two hundred sixty-one thousand, nine hundred sixty-five".