21278832 has 80 divisors (see below), whose sum is σ = 59058720. Its totient is φ = 6578176.

The previous prime is 21278821. The next prime is 21278861. The reversal of 21278832 is 23887212.

It is a junction number, because it is equal to n+sod(n) for n = 21278793 and 21278802.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 72478 + ... + 72770.

It is an arithmetic number, because the mean of its divisors is an integer number (738234).

Almost surely, 2^21278832 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 21278832, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29529360).

21278832 is an abundant number, since it is smaller than the sum of its proper divisors (37779888).

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

21278832 is a wasteful number, since it uses less digits than its factorization.

21278832 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 410 (or 404 counting only the distinct ones).

The product of its digits is 10752, while the sum is 33.

The square root of 21278832 is about 4612.8984380756. The cubic root of 21278832 is about 277.1081263636.

The spelling of 21278832 in words is "twenty-one million, two hundred seventy-eight thousand, eight hundred thirty-two".