21656627 has 2 divisors, whose sum is σ = 21656628. Its totient is φ = 21656626.

The previous prime is 21656597. The next prime is 21656629. The reversal of 21656627 is 72665612.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21656627 is a prime.

Together with 21656629, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21656629) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10828313 + 10828314.

It is an arithmetic number, because the mean of its divisors is an integer number (10828314).

Almost surely, 2^21656627 is an apocalyptic number.

21656627 is a deficient number, since it is larger than the sum of its proper divisors (1).

21656627 is an equidigital number, since it uses as much as digits as its factorization.

21656627 is an evil number, because the sum of its binary digits is even.

The product of its digits is 30240, while the sum is 35.

The square root of 21656627 is about 4653.6681231046. The cubic root of 21656627 is about 278.7384873284.

The spelling of 21656627 in words is "twenty-one million, six hundred fifty-six thousand, six hundred twenty-seven".