21656331725281 has 8 divisors (see below), whose sum is σ = 25014800281824. Its totient is φ = 18529481689920.

The previous prime is 21656331725263. The next prime is 21656331725291. The reversal of 21656331725281 is 18252713365612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21656331725281 is a prime.

It is a super-2 number, since 2×21656331725281² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21656331725291) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 57904630095 + ... + 57904630468.

It is an arithmetic number, because the mean of its divisors is an integer number (3126850035228).

Almost surely, 2^{21656331725281} is an apocalyptic number.

It is an amenable number.

21656331725281 is a deficient number, since it is larger than the sum of its proper divisors (3358468556543).

21656331725281 is a wasteful number, since it uses less digits than its factorization.

21656331725281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 115809260591.

The product of its digits is 3628800, while the sum is 52.

The spelling of 21656331725281 in words is "twenty-one trillion, six hundred fifty-six billion, three hundred thirty-one million, seven hundred twenty-five thousand, two hundred eighty-one".