21561589 has 8 divisors (see below), whose sum is σ = 24671808. Its totient is φ = 18458880.

The previous prime is 21561583. The next prime is 21561601. The reversal of 21561589 is 98516512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21561589 - 2⁹ = 21561077 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21561583) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7254 + ... + 9784.

It is an arithmetic number, because the mean of its divisors is an integer number (3083976).

Almost surely, 2^21561589 is an apocalyptic number.

It is an amenable number.

21561589 is a deficient number, since it is larger than the sum of its proper divisors (3110219).

21561589 is a wasteful number, since it uses less digits than its factorization.

21561589 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3755.

The product of its digits is 21600, while the sum is 37.

The square root of 21561589 is about 4643.4458110330. The cubic root of 21561589 is about 278.3301505208.

The spelling of 21561589 in words is "twenty-one million, five hundred sixty-one thousand, five hundred eighty-nine".