21204630 has 24 divisors (see below), whose sum is σ = 55132272. Its totient is φ = 5654544.

The previous prime is 21204619. The next prime is 21204641. The reversal of 21204630 is 3640212.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21204619) and next prime (21204641).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a Curzon number.

It is a congruent number.

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, 117714 + ... + 117893.

It is an arithmetic number, because the mean of its divisors is an integer number (2297178).

Almost surely, 2^21204630 is an apocalyptic number.

21204630 is an abundant number, since it is smaller than the sum of its proper divisors (33927642).

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

21204630 is a wasteful number, since it uses less digits than its factorization.

21204630 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 235620 (or 235617 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

The square root of 21204630 is about 4604.8485317109. The cubic root of 21204630 is about 276.7856474426.

Adding to 21204630 its reverse (3640212), we get a palindrome (24844842).

The spelling of 21204630 in words is "twenty-one million, two hundred four thousand, six hundred thirty".