21626343256621 has 4 divisors (see below), whose sum is σ = 21695881338144. Its totient is φ = 21556805175100.

The previous prime is 21626343256603. The next prime is 21626343256657. The reversal of 21626343256621 is 12665234362612.

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 21626343256621 - 2¹⁷ = 21626343125549 is a prime.

It is a Smith number, since the sum of its digits (49) 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 (21626343236621) 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, 34769040295 + ... + 34769040916.

It is an arithmetic number, because the mean of its divisors is an integer number (5423970334536).

Almost surely, 2^{21626343256621} is an apocalyptic number.

It is an amenable number.

21626343256621 is a deficient number, since it is larger than the sum of its proper divisors (69538081523).

21626343256621 is an equidigital number, since it uses as much as digits as its factorization.

21626343256621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 69538081522.

The product of its digits is 3732480, while the sum is 49.

The spelling of 21626343256621 in words is "twenty-one trillion, six hundred twenty-six billion, three hundred forty-three million, two hundred fifty-six thousand, six hundred twenty-one".