21656250220642 has 16 divisors (see below), whose sum is σ = 32595769233720. Its totient is φ = 10790995002112.

The previous prime is 21656250220621. The next prime is 21656250220699. The reversal of 21656250220642 is 24602205265612.

It can be written as a sum of positive squares in 4 ways, for example, as 15824889758601 + 5831360462041 = 3978051^2 + 2414821^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 40926468 + ... + 41452240.

Almost surely, 2^{21656250220642} is an apocalyptic number.

21656250220642 is a deficient number, since it is larger than the sum of its proper divisors (10939519013078).

21656250220642 is a wasteful number, since it uses less digits than its factorization.

21656250220642 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 596357.

The product of its (nonzero) digits is 691200, while the sum is 43.

The spelling of 21656250220642 in words is "twenty-one trillion, six hundred fifty-six billion, two hundred fifty million, two hundred twenty thousand, six hundred forty-two".