21965651 has 2 divisors, whose sum is σ = 21965652. Its totient is φ = 21965650.

The previous prime is 21965623. The next prime is 21965659. The reversal of 21965651 is 15656912.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21965651 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21965659) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10982825 + 10982826.

It is an arithmetic number, because the mean of its divisors is an integer number (10982826).

Almost surely, 2^21965651 is an apocalyptic number.

21965651 is a deficient number, since it is larger than the sum of its proper divisors (1).

21965651 is an equidigital number, since it uses as much as digits as its factorization.

21965651 is an evil number, because the sum of its binary digits is even.

The product of its digits is 16200, while the sum is 35.

The square root of 21965651 is about 4686.7527137668. The cubic root of 21965651 is about 280.0580279393.

The spelling of 21965651 in words is "twenty-one million, nine hundred sixty-five thousand, six hundred fifty-one".