21621589 has 16 divisors (see below), whose sum is σ = 24192000. Its totient is φ = 19159920.

The previous prime is 21621577. The next prime is 21621629. The reversal of 21621589 is 98512612.

It is a cyclic number.

It is not a de Polignac number, because 21621589 - 2⁵ = 21621557 is a prime.

It is a super-2 number, since 2×21621589² = 934986221769842, 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 (21621289) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 120702 + ... + 120880.

It is an arithmetic number, because the mean of its divisors is an integer number (1512000).

Almost surely, 2^21621589 is an apocalyptic number.

It is an amenable number.

21621589 is a deficient number, since it is larger than the sum of its proper divisors (2570411).

21621589 is a wasteful number, since it uses less digits than its factorization.

21621589 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 408.

The product of its digits is 8640, while the sum is 34.

The square root of 21621589 is about 4649.9020419789. The cubic root of 21621589 is about 278.5880836227.

The spelling of 21621589 in words is "twenty-one million, six hundred twenty-one thousand, five hundred eighty-nine".