21668963 has 2 divisors, whose sum is σ = 21668964. Its totient is φ = 21668962.

The previous prime is 21668957. The next prime is 21669007. The reversal of 21668963 is 36986612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21668963 - 2¹⁰ = 21667939 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21668963.

It is not a weakly prime, because it can be changed into another prime (21668923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10834481 + 10834482.

It is an arithmetic number, because the mean of its divisors is an integer number (10834482).

Almost surely, 2^21668963 is an apocalyptic number.

21668963 is a deficient number, since it is larger than the sum of its proper divisors (1).

21668963 is an equidigital number, since it uses as much as digits as its factorization.

21668963 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 93312, while the sum is 41.

The square root of 21668963 is about 4654.9933404893. The cubic root of 21668963 is about 278.7914020830.

The spelling of 21668963 in words is "twenty-one million, six hundred sixty-eight thousand, nine hundred sixty-three".