21965563 has 2 divisors, whose sum is σ = 21965564. Its totient is φ = 21965562.

The previous prime is 21965527. The next prime is 21965569. The reversal of 21965563 is 36556912.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21965563 is a prime.

It is not a weakly prime, because it can be changed into another prime (21965569) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10982781 + 10982782.

It is an arithmetic number, because the mean of its divisors is an integer number (10982782).

Almost surely, 2^21965563 is an apocalyptic number.

21965563 is a deficient number, since it is larger than the sum of its proper divisors (1).

21965563 is an equidigital number, since it uses as much as digits as its factorization.

21965563 is an evil number, because the sum of its binary digits is even.

The product of its digits is 48600, while the sum is 37.

The square root of 21965563 is about 4686.7433255940. The cubic root of 21965563 is about 280.0576539442.

The spelling of 21965563 in words is "twenty-one million, nine hundred sixty-five thousand, five hundred sixty-three".