21589521 has 16 divisors (see below), whose sum is σ = 29377920. Its totient is φ = 14100480.

The previous prime is 21589517. The next prime is 21589523. The reversal of 21589521 is 12598512.

It is not a de Polignac number, because 21589521 - 2² = 21589517 is a prime.

It is a super-2 number, since 2×21589521² = 932214834018882, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21589523) 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 15 ways as a sum of consecutive naturals, for example, 33361 + ... + 34001.

It is an arithmetic number, because the mean of its divisors is an integer number (1836120).

Almost surely, 2^21589521 is an apocalyptic number.

It is an amenable number.

21589521 is a deficient number, since it is larger than the sum of its proper divisors (7788399).

21589521 is a wasteful number, since it uses less digits than its factorization.

21589521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 856.

The product of its digits is 7200, while the sum is 33.

The square root of 21589521 is about 4646.4525177817. The cubic root of 21589521 is about 278.4502864269.

The spelling of 21589521 in words is "twenty-one million, five hundred eighty-nine thousand, five hundred twenty-one".