21888740 has 12 divisors (see below), whose sum is σ = 45966396. Its totient is φ = 8755488.

The previous prime is 21888739. The next prime is 21888751. The reversal of 21888740 is 4788812.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 14577124 + 7311616 = 3818^2 + 2704^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21888694 and 21888703.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 547199 + ... + 547238.

It is an arithmetic number, because the mean of its divisors is an integer number (3830533).

Almost surely, 2^21888740 is an apocalyptic number.

21888740 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21888740 is an abundant number, since it is smaller than the sum of its proper divisors (24077656).

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

21888740 is a wasteful number, since it uses less digits than its factorization.

21888740 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1094446 (or 1094444 counting only the distinct ones).

The product of its (nonzero) digits is 28672, while the sum is 38.

The square root of 21888740 is about 4678.5403706712. The cubic root of 21888740 is about 279.7307786403.

The spelling of 21888740 in words is "twenty-one million, eight hundred eighty-eight thousand, seven hundred forty".