21839856 has 40 divisors (see below), whose sum is σ = 57270144. Its totient is φ = 7170240.

The previous prime is 21839837. The next prime is 21839863. The reversal of 21839856 is 65893812.

It is a congruent number.

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, 180 + ... + 6611.

Almost surely, 2^21839856 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 21839856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28635072).

21839856 is an abundant number, since it is smaller than the sum of its proper divisors (35430288).

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

21839856 is a wasteful number, since it uses less digits than its factorization.

21839856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6869 (or 6863 counting only the distinct ones).

The product of its digits is 103680, while the sum is 42.

The square root of 21839856 is about 4673.3131716160. The cubic root of 21839856 is about 279.5223830351.

The spelling of 21839856 in words is "twenty-one million, eight hundred thirty-nine thousand, eight hundred fifty-six".