21635969 has 2 divisors, whose sum is σ = 21635970. Its totient is φ = 21635968.

The previous prime is 21635941. The next prime is 21635983. The reversal of 21635969 is 96953612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14938225 + 6697744 = 3865^2 + 2588^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21635969 is a prime.

It is a super-2 number, since 2×21635969² = 936230309137922, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21635069) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10817984 + 10817985.

It is an arithmetic number, because the mean of its divisors is an integer number (10817985).

Almost surely, 2^21635969 is an apocalyptic number.

It is an amenable number.

21635969 is a deficient number, since it is larger than the sum of its proper divisors (1).

21635969 is an equidigital number, since it uses as much as digits as its factorization.

21635969 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 87480, while the sum is 41.

The square root of 21635969 is about 4651.4480541010. The cubic root of 21635969 is about 278.6498306857.

The spelling of 21635969 in words is "twenty-one million, six hundred thirty-five thousand, nine hundred sixty-nine".