21630400 has 84 divisors (see below), whose sum is σ = 58110120. Its totient is φ = 7859200.

The previous prime is 21630391. The next prime is 21630421. The reversal of 21630400 is 403612.

It is a Harshad number since it is a multiple of its sum of digits (16).

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, 16986 + ... + 18214.

Almost surely, 2^21630400 is an apocalyptic number.

21630400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21630400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29055060).

21630400 is an abundant number, since it is smaller than the sum of its proper divisors (36479720).

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

21630400 is a wasteful number, since it uses less digits than its factorization.

21630400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1262 (or 1247 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 16.

The square root of 21630400 is about 4650.8493847898. The cubic root of 21630400 is about 278.6259209012.

The spelling of 21630400 in words is "twenty-one million, six hundred thirty thousand, four hundred".