21897372 has 48 divisors (see below), whose sum is σ = 59209472. Its totient is φ = 6168960.

The previous prime is 21897371. The next prime is 21897373. The reversal of 21897372 is 27379812.

It is an interprime number because it is at equal distance from previous prime (21897371) and next prime (21897373).

It is a self number, because there is not a number n which added to its sum of digits gives 21897372.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21897371) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4347 + ... + 7917.

Almost surely, 2^21897372 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21897372, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29604736).

21897372 is an abundant number, since it is smaller than the sum of its proper divisors (37312100).

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

21897372 is a wasteful number, since it uses less digits than its factorization.

21897372 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3658 (or 3656 counting only the distinct ones).

The product of its digits is 42336, while the sum is 39.

The square root of 21897372 is about 4679.4627896800. The cubic root of 21897372 is about 279.7675451656.

The spelling of 21897372 in words is "twenty-one million, eight hundred ninety-seven thousand, three hundred seventy-two".