21626330666521 has 4 divisors (see below), whose sum is σ = 24715806476032. Its totient is φ = 18536854857012.

The previous prime is 21626330666489. The next prime is 21626330666537. The reversal of 21626330666521 is 12566603362612.

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 21626330666521 - 2⁵ = 21626330666489 is a prime.

It is a super-2 number, since 2×21626330666521² (a number of 27 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21626330666021) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1544737904745 + ... + 1544737904758.

It is an arithmetic number, because the mean of its divisors is an integer number (6178951619008).

Almost surely, 2^{21626330666521} is an apocalyptic number.

It is an amenable number.

21626330666521 is a deficient number, since it is larger than the sum of its proper divisors (3089475809511).

21626330666521 is an equidigital number, since it uses as much as digits as its factorization.

21626330666521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3089475809510.

The product of its (nonzero) digits is 2799360, while the sum is 49.

The spelling of 21626330666521 in words is "twenty-one trillion, six hundred twenty-six billion, three hundred thirty million, six hundred sixty-six thousand, five hundred twenty-one".