21565432 has 32 divisors (see below), whose sum is σ = 46648800. Its totient is φ = 9154944.

The previous prime is 21565417. The next prime is 21565447. The reversal of 21565432 is 23456512.

It is an interprime number because it is at equal distance from previous prime (21565417) and next prime (21565447).

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a self number, because there is not a number n which added to its sum of digits gives 21565432.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4338 + ... + 7870.

It is an arithmetic number, because the mean of its divisors is an integer number (1457775).

Almost surely, 2^21565432 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21565432, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23324400).

21565432 is an abundant number, since it is smaller than the sum of its proper divisors (25083368).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21565432 is a wasteful number, since it uses less digits than its factorization.

21565432 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3655 (or 3651 counting only the distinct ones).

The product of its digits is 7200, while the sum is 28.

The square root of 21565432 is about 4643.8596016676. The cubic root of 21565432 is about 278.3466854683.

The spelling of 21565432 in words is "twenty-one million, five hundred sixty-five thousand, four hundred thirty-two".