21522001521 has 16 divisors (see below), whose sum is σ = 29065512960. Its totient is φ = 14163324240.

The previous prime is 21522001493. The next prime is 21522001559. The reversal of 21522001521 is 12510022512.

It is not a de Polignac number, because 21522001521 - 2¹⁰ = 21522000497 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21522001561) 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, 1776916 + ... + 1788986.

It is an arithmetic number, because the mean of its divisors is an integer number (1816594560).

Almost surely, 2^21522001521 is an apocalyptic number.

It is an amenable number.

21522001521 is a deficient number, since it is larger than the sum of its proper divisors (7543511439).

21522001521 is a wasteful number, since it uses less digits than its factorization.

21522001521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19676.

The product of its (nonzero) digits is 400, while the sum is 21.

The spelling of 21522001521 in words is "twenty-one billion, five hundred twenty-two million, one thousand, five hundred twenty-one".