21215562523021 has 4 divisors (see below), whose sum is σ = 21215593836544. Its totient is φ = 21215531209500.

The previous prime is 21215562522857. The next prime is 21215562523081. The reversal of 21215562523021 is 12032526551212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21215562523021 - 2¹¹ = 21215562520973 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21215562523081) 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 3 ways as a sum of consecutive naturals, for example, 14617485 + ... + 16003186.

It is an arithmetic number, because the mean of its divisors is an integer number (5303898459136).

Almost surely, 2^{21215562523021} is an apocalyptic number.

It is an amenable number.

21215562523021 is a deficient number, since it is larger than the sum of its proper divisors (31313523).

21215562523021 is an equidigital number, since it uses as much as digits as its factorization.

21215562523021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31313522.

The product of its (nonzero) digits is 72000, while the sum is 37.

The spelling of 21215562523021 in words is "twenty-one trillion, two hundred fifteen billion, five hundred sixty-two million, five hundred twenty-three thousand, twenty-one".