21938760 has 96 divisors (see below), whose sum is σ = 71955000. Its totient is φ = 5796864.

The previous prime is 21938759. The next prime is 21938771. The reversal of 21938760 is 6783912.

21938760 is a `hidden beast` number, since 219 + 387 + 60 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 17994564 + 3944196 = 4242^2 + 1986^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 53436 + ... + 53844.

Almost surely, 2^21938760 is an apocalyptic number.

21938760 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 21938760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35977500).

21938760 is an abundant number, since it is smaller than the sum of its proper divisors (50016240).

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

21938760 is a wasteful number, since it uses less digits than its factorization.

21938760 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 575 (or 568 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 36.

The square root of 21938760 is about 4683.8830045167. The cubic root of 21938760 is about 279.9436961619.

The spelling of 21938760 in words is "twenty-one million, nine hundred thirty-eight thousand, seven hundred sixty".