21315800 has 48 divisors (see below), whose sum is σ = 54070200. Its totient is φ = 7750400.

The previous prime is 21315799. The next prime is 21315803. The reversal of 21315800 is 851312.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21315803) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2645 + ... + 7044.

Almost surely, 2^21315800 is an apocalyptic number.

21315800 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21315800 is an abundant number, since it is smaller than the sum of its proper divisors (32754400).

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

21315800 is a wasteful number, since it uses less digits than its factorization.

21315800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9716 (or 9707 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 20.

The square root of 21315800 is about 4616.9037243590. The cubic root of 21315800 is about 277.2685080755.

The spelling of 21315800 in words is "twenty-one million, three hundred fifteen thousand, eight hundred".