21559902 has 48 divisors (see below), whose sum is σ = 54027792. Its totient is φ = 5685120.

The previous prime is 21559897. The next prime is 21559903. The reversal of 21559902 is 20995512.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21559903) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1002 + ... + 6642.

It is an arithmetic number, because the mean of its divisors is an integer number (1125579).

Almost surely, 2^21559902 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21559902, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27013896).

21559902 is an abundant number, since it is smaller than the sum of its proper divisors (32467890).

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

21559902 is a wasteful number, since it uses less digits than its factorization.

21559902 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5673 (or 5666 counting only the distinct ones).

The product of its (nonzero) digits is 8100, while the sum is 33.

The square root of 21559902 is about 4643.2641535885. The cubic root of 21559902 is about 278.3228913896.

The spelling of 21559902 in words is "twenty-one million, five hundred fifty-nine thousand, nine hundred two".