21590217 has 12 divisors (see below), whose sum is σ = 34021104. Its totient is φ = 13084920.

The previous prime is 21590201. The next prime is 21590237. The reversal of 21590217 is 71209512.

It is not a de Polignac number, because 21590217 - 2⁴ = 21590201 is a prime.

It is a super-2 number, since 2×21590217² = 932274940214178, which contains 22 as substring.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21590237) 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 in 11 ways as a sum of consecutive naturals, for example, 108943 + ... + 109140.

It is an arithmetic number, because the mean of its divisors is an integer number (2835092).

Almost surely, 2^21590217 is an apocalyptic number.

It is an amenable number.

21590217 is a deficient number, since it is larger than the sum of its proper divisors (12430887).

21590217 is a wasteful number, since it uses less digits than its factorization.

21590217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 218100 (or 218097 counting only the distinct ones).

The product of its (nonzero) digits is 1260, while the sum is 27.

The square root of 21590217 is about 4646.5274130258. The cubic root of 21590217 is about 278.4532786087.

Adding to 21590217 its reverse (71209512), we get a palindrome (92799729).

The spelling of 21590217 in words is "twenty-one million, five hundred ninety thousand, two hundred seventeen".