216561800 has 192 divisors, whose sum is σ = 632042880. Its totient is φ = 67184640.

The previous prime is 216561799. The next prime is 216561817. The reversal of 216561800 is 8165612.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1328519 + ... + 1328681.

It is an arithmetic number, because the mean of its divisors is an integer number (3291890).

Almost surely, 2^216561800 is an apocalyptic number.

216561800 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 216561800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (316021440).

216561800 is an abundant number, since it is smaller than the sum of its proper divisors (415481080).

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

216561800 is a wasteful number, since it uses less digits than its factorization.

216561800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 272 (or 263 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 29.

The square root of 216561800 is about 14716.0388692066. The cubic root of 216561800 is about 600.5197348480.

The spelling of 216561800 in words is "two hundred sixteen million, five hundred sixty-one thousand, eight hundred".