21556873271844 has 135 divisors (see below), whose sum is σ = 59867803597987. Its totient is φ = 6762494912256.

The previous prime is 21556873271837. The next prime is 21556873271851. The reversal of 21556873271844 is 44817237865512.

The square root of 21556873271844 is 4642938.

It is a perfect power (a square), and thus also a powerful number.

21556873271844 is a `hidden beast` number, since 2 + 1 + 5 + 56 + 87 + 327 + 184 + 4 = 666.

It is an interprime number because it is at equal distance from previous prime (21556873271837) and next prime (21556873271851).

It can be written as a sum of positive squares in 4 ways, for example, as 11177908982244 + 10378964289600 = 3343338^2 + 3221640^2 .

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 1420731442 + ... + 1420746614.

Almost surely, 2^{21556873271844} is an apocalyptic number.

21556873271844 is the 4642938-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21556873271844

21556873271844 is an abundant number, since it is smaller than the sum of its proper divisors (38310930326143).

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

21556873271844 is an frugal number, since it uses more digits than its factorization.

21556873271844 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30396 (or 15195 counting only the distinct ones).

The product of its digits is 90316800, while the sum is 63.

The spelling of 21556873271844 in words is "twenty-one trillion, five hundred fifty-six billion, eight hundred seventy-three million, two hundred seventy-one thousand, eight hundred forty-four".