21379520 has 56 divisors (see below), whose sum is σ = 51681888. Its totient is φ = 8422400.

The previous prime is 21379517. The next prime is 21379531. The reversal of 21379520 is 2597312.

It is a hoax number, since the sum of its digits (29) coincides with the sum of the digits of its distinct prime factors.

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, 22250 + ... + 23190.

Almost surely, 2^21379520 is an apocalyptic number.

21379520 is a gapful number since it is divisible by the number (20) 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 21379520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25840944).

21379520 is an abundant number, since it is smaller than the sum of its proper divisors (30302368).

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

21379520 is an equidigital number, since it uses as much as digits as its factorization.

21379520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1029 (or 1019 counting only the distinct ones).

The product of its (nonzero) digits is 3780, while the sum is 29.

The square root of 21379520 is about 4623.7993036030. The cubic root of 21379520 is about 277.5445157598.

The spelling of 21379520 in words is "twenty-one million, three hundred seventy-nine thousand, five hundred twenty".