21590397 has 12 divisors (see below), whose sum is σ = 31237180. Its totient is φ = 14370048.

The previous prime is 21590369. The next prime is 21590411. The reversal of 21590397 is 79309512.

It can be written as a sum of positive squares in 2 ways, for example, as 15729156 + 5861241 = 3966^2 + 2421^2 .

It is not a de Polignac number, because 21590397 - 2¹⁴ = 21574013 is a prime.

It is a super-2 number, since 2×21590397² = 932290485235218, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21090397) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5229 + ... + 8397.

Almost surely, 2^21590397 is an apocalyptic number.

It is an amenable number.

21590397 is a deficient number, since it is larger than the sum of its proper divisors (9646783).

21590397 is a wasteful number, since it uses less digits than its factorization.

21590397 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3932 (or 3929 counting only the distinct ones).

The product of its (nonzero) digits is 17010, while the sum is 36.

The square root of 21590397 is about 4646.5467822890. The cubic root of 21590397 is about 278.4540524383.

It can be divided in two parts, 215903 and 97, that added together give a cube (216000 = 60³).

The spelling of 21590397 in words is "twenty-one million, five hundred ninety thousand, three hundred ninety-seven".