21637661254 has 16 divisors (see below), whose sum is σ = 35409370320. Its totient is φ = 9834664960.

The previous prime is 21637661207. The next prime is 21637661273. The reversal of 21637661254 is 45216673612.

It is a self number, because there is not a number n which added to its sum of digits gives 21637661254.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 567462 + ... + 604390.

It is an arithmetic number, because the mean of its divisors is an integer number (2213085645).

Almost surely, 2^21637661254 is an apocalyptic number.

21637661254 is a deficient number, since it is larger than the sum of its proper divisors (13771709066).

21637661254 is a wasteful number, since it uses less digits than its factorization.

21637661254 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63575.

The product of its digits is 362880, while the sum is 43.

The spelling of 21637661254 in words is "twenty-one billion, six hundred thirty-seven million, six hundred sixty-one thousand, two hundred fifty-four".