21918464 has 18 divisors (see below), whose sum is σ = 43751820. Its totient is φ = 10959104.

The previous prime is 21918443. The next prime is 21918473. The reversal of 21918464 is 46481912.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 42554 + ... + 43065.

Almost surely, 2^21918464 is an apocalyptic number.

It is an amenable number.

21918464 is a deficient number, since it is larger than the sum of its proper divisors (21833356).

21918464 is an frugal number, since it uses more digits than its factorization.

21918464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85635 (or 85621 counting only the distinct ones).

The product of its digits is 13824, while the sum is 35.

The square root of 21918464 is about 4681.7159247438. The cubic root of 21918464 is about 279.8573422954.

The spelling of 21918464 in words is "twenty-one million, nine hundred eighteen thousand, four hundred sixty-four".