21516800 has 90 divisors (see below), whose sum is σ = 54641499. Its totient is φ = 8396800.

The previous prime is 21516791. The next prime is 21516827. The reversal of 21516800 is 861512.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It can be written as a sum of positive squares in 5 ways, for example, as 135424 + 21381376 = 368^2 + 4624^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=3280.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 524780 + ... + 524820.

Almost surely, 2^21516800 is an apocalyptic number.

21516800 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 21516800

21516800 is an abundant number, since it is smaller than the sum of its proper divisors (33124699).

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

21516800 is an frugal number, since it uses more digits than its factorization.

21516800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 110 (or 48 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 23.

The square root of 21516800 is about 4638.6204845838. The cubic root of 21516800 is about 278.1372956732.

The spelling of 21516800 in words is "twenty-one million, five hundred sixteen thousand, eight hundred".