21154275664 has 20 divisors (see below), whose sum is σ = 41005512756. Its totient is φ = 10572207872.

The previous prime is 21154275661. The next prime is 21154275671. The reversal of 21154275664 is 46657245112.

It can be written as a sum of positive squares in 2 ways, for example, as 4459568400 + 16694707264 = 66780^2 + 129208^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21154275664.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21154275661) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 272599 + ... + 341494.

Almost surely, 2^21154275664 is an apocalyptic number.

It is an amenable number.

21154275664 is a deficient number, since it is larger than the sum of its proper divisors (19851237092).

21154275664 is a wasteful number, since it uses less digits than its factorization.

21154275664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 616254 (or 616248 counting only the distinct ones).

The product of its digits is 403200, while the sum is 43.

The spelling of 21154275664 in words is "twenty-one billion, one hundred fifty-four million, two hundred seventy-five thousand, six hundred sixty-four".