21881464 has 64 divisors (see below), whose sum is σ = 49248000. Its totient is φ = 8997120.

The previous prime is 21881459. The next prime is 21881477. The reversal of 21881464 is 46418812.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 38172 + ... + 38740.

It is an arithmetic number, because the mean of its divisors is an integer number (769500).

Almost surely, 2^21881464 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 21881464, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24624000).

21881464 is an abundant number, since it is smaller than the sum of its proper divisors (27366536).

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

21881464 is a wasteful number, since it uses less digits than its factorization.

21881464 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 628 (or 624 counting only the distinct ones).

The product of its digits is 12288, while the sum is 34.

The square root of 21881464 is about 4677.7627130927. The cubic root of 21881464 is about 279.6997802562.

The spelling of 21881464 in words is "twenty-one million, eight hundred eighty-one thousand, four hundred sixty-four".