216643680 has 384 divisors, whose sum is σ = 853493760. Its totient is φ = 50872320.

The previous prime is 216643673. The next prime is 216643697. The reversal of 216643680 is 86346612.

216643680 is a `hidden beast` number, since 2 + 1 + 6 + 643 + 6 + 8 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 2233392 + ... + 2233488.

It is an arithmetic number, because the mean of its divisors is an integer number (2222640).

Almost surely, 2^216643680 is an apocalyptic number.

216643680 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 216643680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (426746880).

216643680 is an abundant number, since it is smaller than the sum of its proper divisors (636850080).

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

216643680 is a wasteful number, since it uses less digits than its factorization.

216643680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 179 (or 165 counting only the distinct ones).

The product of its (nonzero) digits is 41472, while the sum is 36.

The square root of 216643680 is about 14718.8206049262. The cubic root of 216643680 is about 600.5954089515.

The spelling of 216643680 in words is "two hundred sixteen million, six hundred forty-three thousand, six hundred eighty".