21938220 has 72 divisors (see below), whose sum is σ = 66930864. Its totient is φ = 5816448.

The previous prime is 21938207. The next prime is 21938243. The reversal of 21938220 is 2283912.

It is a happy number.

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, 55062 + ... + 55458.

It is a vampire number, since it can be written as 2382 ⋅ 9210 (with its own digits).

Almost surely, 2^21938220 is an apocalyptic number.

21938220 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 21938220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33465432).

21938220 is an abundant number, since it is smaller than the sum of its proper divisors (44992644).

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

21938220 is a wasteful number, since it uses less digits than its factorization.

21938220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 719 (or 714 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 21938220 is about 4683.8253596820. The cubic root of 21938220 is about 279.9413993010.

The spelling of 21938220 in words is "twenty-one million, nine hundred thirty-eight thousand, two hundred twenty".