21531062821557 has 16 divisors (see below), whose sum is σ = 29375951578688. Its totient is φ = 14020113381120.

The previous prime is 21531062821493. The next prime is 21531062821579. The reversal of 21531062821557 is 75512826013512.

It is not a de Polignac number, because 21531062821557 - 2⁶ = 21531062821493 is a prime.

It is a Smith number, since the sum of its digits (48) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21531062822557) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17118957 + ... + 18333597.

It is an arithmetic number, because the mean of its divisors is an integer number (1835996973668).

Almost surely, 2^{21531062821557} is an apocalyptic number.

It is an amenable number.

21531062821557 is a deficient number, since it is larger than the sum of its proper divisors (7844888757131).

21531062821557 is a wasteful number, since it uses less digits than its factorization.

21531062821557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1352100.

The product of its (nonzero) digits is 1008000, while the sum is 48.

The spelling of 21531062821557 in words is "twenty-one trillion, five hundred thirty-one billion, sixty-two million, eight hundred twenty-one thousand, five hundred fifty-seven".