21888644 has 6 divisors (see below), whose sum is σ = 38305134. Its totient is φ = 10944320.

The previous prime is 21888623. The next prime is 21888653. The reversal of 21888644 is 44688812.

It can be written as a sum of positive squares in only one way, i.e., 18232900 + 3655744 = 4270^2 + 1912^2 .

It is a super-2 number, since 2×21888644² = 958225472317472, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2736077 + ... + 2736084.

It is an arithmetic number, because the mean of its divisors is an integer number (6384189).

Almost surely, 2^21888644 is an apocalyptic number.

It is an amenable number.

21888644 is a deficient number, since it is larger than the sum of its proper divisors (16416490).

21888644 is a wasteful number, since it uses less digits than its factorization.

21888644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5472165 (or 5472163 counting only the distinct ones).

The product of its digits is 98304, while the sum is 41.

The square root of 21888644 is about 4678.5301110498. The cubic root of 21888644 is about 279.7303696904.

The spelling of 21888644 in words is "twenty-one million, eight hundred eighty-eight thousand, six hundred forty-four".