21820604 has 30 divisors (see below), whose sum is σ = 41584704. Its totient is φ = 10018320.

The previous prime is 21820597. The next prime is 21820613. The reversal of 21820604 is 40602812.

21820604 = 272² + 273² + ... + 440².

It is a super-2 number, since 2×21820604² = 952277517849632, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21820604.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 114149 + ... + 114339.

Almost surely, 2^21820604 is an apocalyptic number.

It is an amenable number.

21820604 is a deficient number, since it is larger than the sum of its proper divisors (19764100).

21820604 is an equidigital number, since it uses as much as digits as its factorization.

21820604 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 247 (or 206 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 23.

The square root of 21820604 is about 4671.2529368468. The cubic root of 21820604 is about 279.4402251837.

The spelling of 21820604 in words is "twenty-one million, eight hundred twenty thousand, six hundred four".