21967651 has 2 divisors, whose sum is σ = 21967652. Its totient is φ = 21967650.

The previous prime is 21967637. The next prime is 21967657. The reversal of 21967651 is 15676912.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21967651 - 2⁵ = 21967619 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21967651.

It is not a weakly prime, because it can be changed into another prime (21967657) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10983825 + 10983826.

It is an arithmetic number, because the mean of its divisors is an integer number (10983826).

Almost surely, 2^21967651 is an apocalyptic number.

21967651 is a deficient number, since it is larger than the sum of its proper divisors (1).

21967651 is an equidigital number, since it uses as much as digits as its factorization.

21967651 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 22680, while the sum is 37.

The square root of 21967651 is about 4686.9660762587. The cubic root of 21967651 is about 280.0665275593.

The spelling of 21967651 in words is "twenty-one million, nine hundred sixty-seven thousand, six hundred fifty-one".