21608969 has 2 divisors, whose sum is σ = 21608970. Its totient is φ = 21608968.

The previous prime is 21608963. The next prime is 21608987. The reversal of 21608969 is 96980612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18386944 + 3222025 = 4288^2 + 1795^2 .

It is a cyclic number.

It is not a de Polignac number, because 21608969 - 2¹² = 21604873 is a prime.

It is a super-2 number, since 2×21608969² = 933895082485922, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21608963) 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, 10804484 + 10804485.

It is an arithmetic number, because the mean of its divisors is an integer number (10804485).

Almost surely, 2^21608969 is an apocalyptic number.

It is an amenable number.

21608969 is a deficient number, since it is larger than the sum of its proper divisors (1).

21608969 is an equidigital number, since it uses as much as digits as its factorization.

21608969 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 46656, while the sum is 41.

The square root of 21608969 is about 4648.5448260719. The cubic root of 21608969 is about 278.5338713589.

The spelling of 21608969 in words is "twenty-one million, six hundred eight thousand, nine hundred sixty-nine".