21589637 has 2 divisors, whose sum is σ = 21589638. Its totient is φ = 21589636.

The previous prime is 21589627. The next prime is 21589639. The reversal of 21589637 is 73698512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20666116 + 923521 = 4546^2 + 961^2 .

It is a cyclic number.

It is not a de Polignac number, because 21589637 - 2²⁴ = 4812421 is a prime.

It is a super-2 number, since 2×21589637² = 932224851583538, which contains 22 as substring.

Together with 21589639, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21589594 and 21589603.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21589639) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10794818 + 10794819.

It is an arithmetic number, because the mean of its divisors is an integer number (10794819).

Almost surely, 2^21589637 is an apocalyptic number.

It is an amenable number.

21589637 is a deficient number, since it is larger than the sum of its proper divisors (1).

21589637 is an equidigital number, since it uses as much as digits as its factorization.

21589637 is an evil number, because the sum of its binary digits is even.

The product of its digits is 90720, while the sum is 41.

The square root of 21589637 is about 4646.4650004062. The cubic root of 21589637 is about 278.4507851283.

The spelling of 21589637 in words is "twenty-one million, five hundred eighty-nine thousand, six hundred thirty-seven".