21307800 has 96 divisors (see below), whose sum is σ = 69973200. Its totient is φ = 5345280.

The previous prime is 21307771. The next prime is 21307807. The reversal of 21307800 is 870312.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21307807) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 9156 + ... + 11244.

Almost surely, 2^21307800 is an apocalyptic number.

21307800 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 21307800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34986600).

21307800 is an abundant number, since it is smaller than the sum of its proper divisors (48665400).

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

21307800 is a wasteful number, since it uses less digits than its factorization.

21307800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2125 (or 2116 counting only the distinct ones).

The product of its (nonzero) digits is 336, while the sum is 21.

The square root of 21307800 is about 4616.0372615480. The cubic root of 21307800 is about 277.2338166632.

The spelling of 21307800 in words is "twenty-one million, three hundred seven thousand, eight hundred".