21812764 has 6 divisors (see below), whose sum is σ = 38172344. Its totient is φ = 10906380.

The previous prime is 21812759. The next prime is 21812783. The reversal of 21812764 is 46721812.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2726592 + ... + 2726599.

Almost surely, 2^21812764 is an apocalyptic number.

It is an amenable number.

21812764 is a deficient number, since it is larger than the sum of its proper divisors (16359580).

21812764 is a wasteful number, since it uses less digits than its factorization.

21812764 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5453195 (or 5453193 counting only the distinct ones).

The product of its digits is 5376, while the sum is 31.

The square root of 21812764 is about 4670.4136861738. The cubic root of 21812764 is about 279.4067541610.

The spelling of 21812764 in words is "twenty-one million, eight hundred twelve thousand, seven hundred sixty-four".