21806963 has 2 divisors, whose sum is σ = 21806964. Its totient is φ = 21806962.

The previous prime is 21806929. The next prime is 21806987. The reversal of 21806963 is 36960812.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21806963 - 2²² = 17612659 is a prime.

It is not a weakly prime, because it can be changed into another prime (21806063) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10903481 + 10903482.

It is an arithmetic number, because the mean of its divisors is an integer number (10903482).

Almost surely, 2^21806963 is an apocalyptic number.

21806963 is a deficient number, since it is larger than the sum of its proper divisors (1).

21806963 is an equidigital number, since it uses as much as digits as its factorization.

21806963 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 15552, while the sum is 35.

The square root of 21806963 is about 4669.7926078146. The cubic root of 21806963 is about 279.3819830027.

The spelling of 21806963 in words is "twenty-one million, eight hundred six thousand, nine hundred sixty-three".