21839538 has 16 divisors (see below), whose sum is σ = 49919040. Its totient is φ = 6239856.

The previous prime is 21839507. The next prime is 21839557. The reversal of 21839538 is 83593812.

It is a junction number, because it is equal to n+sod(n) for n = 21839496 and 21839505.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 259953 + ... + 260036.

It is an arithmetic number, because the mean of its divisors is an integer number (3119940).

Almost surely, 2^21839538 is an apocalyptic number.

21839538 is an abundant number, since it is smaller than the sum of its proper divisors (28079502).

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

21839538 is a wasteful number, since it uses less digits than its factorization.

21839538 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 520001.

The product of its digits is 51840, while the sum is 39.

The square root of 21839538 is about 4673.2791485209. The cubic root of 21839538 is about 279.5210263633.

The spelling of 21839538 in words is "twenty-one million, eight hundred thirty-nine thousand, five hundred thirty-eight".