21938900 has 18 divisors (see below), whose sum is σ = 47607630. Its totient is φ = 8775520.

The previous prime is 21938899. The next prime is 21938923. The reversal of 21938900 is 983912.

It can be written as a sum of positive squares in 3 ways, for example, as 1993744 + 19945156 = 1412^2 + 4466^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 109595 + ... + 109794.

Almost surely, 2^21938900 is an apocalyptic number.

21938900 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21938900 is an abundant number, since it is smaller than the sum of its proper divisors (25668730).

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

21938900 is a wasteful number, since it uses less digits than its factorization.

21938900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 219403 (or 219396 counting only the distinct ones).

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

The square root of 21938900 is about 4683.8979493580. The cubic root of 21938900 is about 279.9442916382.

The spelling of 21938900 in words is "twenty-one million, nine hundred thirty-eight thousand, nine hundred".