21890664 has 48 divisors (see below), whose sum is σ = 61869600. Its totient is φ = 6979104.

The previous prime is 21890651. The next prime is 21890677. The reversal of 21890664 is 46609812.

It is an interprime number because it is at equal distance from previous prime (21890651) and next prime (21890677).

It is a Harshad number since it is a multiple of its sum of digits (36).

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, 4954 + ... + 8265.

It is an arithmetic number, because the mean of its divisors is an integer number (1288950).

Almost surely, 2^21890664 is an apocalyptic number.

21890664 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21890664 is an abundant number, since it is smaller than the sum of its proper divisors (39978936).

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

21890664 is a wasteful number, since it uses less digits than its factorization.

21890664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13254 (or 13247 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 36.

The square root of 21890664 is about 4678.7459858385. The cubic root of 21890664 is about 279.7389744257.

The spelling of 21890664 in words is "twenty-one million, eight hundred ninety thousand, six hundred sixty-four".