21939008 has 56 divisors (see below), whose sum is σ = 53596032. Its totient is φ = 8676864.

The previous prime is 21939007. The next prime is 21939017. The reversal of 21939008 is 80093912.

It is a tau number, because it is divible by the number of its divisors (56).

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21939007) 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, 3941 + ... + 7707.

It is an arithmetic number, because the mean of its divisors is an integer number (957072).

Almost surely, 2^21939008 is an apocalyptic number.

21939008 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21939008, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26798016).

21939008 is an abundant number, since it is smaller than the sum of its proper divisors (31657024).

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

21939008 is a wasteful number, since it uses less digits than its factorization.

21939008 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3799 (or 3789 counting only the distinct ones).

The product of its (nonzero) digits is 3888, while the sum is 32.

The square root of 21939008 is about 4683.9094782030. The cubic root of 21939008 is about 279.9447510039.

The spelling of 21939008 in words is "twenty-one million, nine hundred thirty-nine thousand, eight".