21557702621 has 16 divisors (see below), whose sum is σ = 26967523968. Its totient is φ = 16777022400.

The previous prime is 21557702611. The next prime is 21557702659. The reversal of 21557702621 is 12620775512.

It is a cyclic number.

It is not a de Polignac number, because 21557702621 - 2¹⁰ = 21557701597 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21557702611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1936235 + ... + 1947336.

It is an arithmetic number, because the mean of its divisors is an integer number (1685470248).

Almost surely, 2^21557702621 is an apocalyptic number.

It is an amenable number.

21557702621 is a deficient number, since it is larger than the sum of its proper divisors (5409821347).

21557702621 is a wasteful number, since it uses less digits than its factorization.

21557702621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3883652.

The product of its (nonzero) digits is 58800, while the sum is 38.

The spelling of 21557702621 in words is "twenty-one billion, five hundred fifty-seven million, seven hundred two thousand, six hundred twenty-one".