216991320 has 256 divisors, whose sum is σ = 828334080. Its totient is φ = 44236800.

The previous prime is 216991309. The next prime is 216991367. The reversal of 216991320 is 23199612.

216991320 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 338200 + ... + 338840.

It is an arithmetic number, because the mean of its divisors is an integer number (3235680).

Almost surely, 2^216991320 is an apocalyptic number.

216991320 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 216991320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (414167040).

216991320 is an abundant number, since it is smaller than the sum of its proper divisors (611342760).

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

216991320 is a wasteful number, since it uses less digits than its factorization.

216991320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 706 (or 702 counting only the distinct ones).

The product of its (nonzero) digits is 5832, while the sum is 33.

The square root of 216991320 is about 14730.6252413127. The cubic root of 216991320 is about 600.9164882582.

The spelling of 216991320 in words is "two hundred sixteen million, nine hundred ninety-one thousand, three hundred twenty".