21897400 has 48 divisors (see below), whose sum is σ = 58188240. Its totient is φ = 7507200.

The previous prime is 21897397. The next prime is 21897431. The reversal of 21897400 is 479812.

It is a super-2 number, since 2×21897400² = 958992253520000, which contains 22 as substring.

It is a hoax number, since the sum of its digits (31) 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 11 ways as a sum of consecutive naturals, for example, 6421 + ... + 9220.

It is an arithmetic number, because the mean of its divisors is an integer number (1212255).

Almost surely, 2^21897400 is an apocalyptic number.

21897400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21897400 is an abundant number, since it is smaller than the sum of its proper divisors (36290840).

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

21897400 is a wasteful number, since it uses less digits than its factorization.

21897400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15664 (or 15655 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 31.

The square root of 21897400 is about 4679.4657814755. The cubic root of 21897400 is about 279.7676644111.

The spelling of 21897400 in words is "twenty-one million, eight hundred ninety-seven thousand, four hundred".