21562621 has 2 divisors, whose sum is σ = 21562622. Its totient is φ = 21562620.

The previous prime is 21562609. The next prime is 21562633. The reversal of 21562621 is 12626512.

It is a balanced prime because it is at equal distance from previous prime (21562609) and next prime (21562633).

It can be written as a sum of positive squares in only one way, i.e., 19236996 + 2325625 = 4386^2 + 1525^2 .

It is a cyclic number.

It is not a de Polignac number, because 21562621 - 2⁵ = 21562589 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21562691) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10781310 + 10781311.

It is an arithmetic number, because the mean of its divisors is an integer number (10781311).

Almost surely, 2^21562621 is an apocalyptic number.

It is an amenable number.

21562621 is a deficient number, since it is larger than the sum of its proper divisors (1).

21562621 is an equidigital number, since it uses as much as digits as its factorization.

21562621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1440, while the sum is 25.

The square root of 21562621 is about 4643.5569340754. The cubic root of 21562621 is about 278.3345910119.

The spelling of 21562621 in words is "twenty-one million, five hundred sixty-two thousand, six hundred twenty-one".