216791640 has 160 divisors (see below), whose sum is σ = 784864080. Its totient is φ = 53353728.

The previous prime is 216791609. The next prime is 216791647. The reversal of 216791640 is 46197612.

216791640 is a `hidden beast` number, since 2 + 1 + 6 + 7 + 9 + 1 + 640 = 666.

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

It is a junction number, because it is equal to n+sod(n) for n = 216791595 and 216791604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216791647) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 39547 + ... + 44693.

Almost surely, 2^216791640 is an apocalyptic number.

216791640 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 216791640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (392432040).

216791640 is an abundant number, since it is smaller than the sum of its proper divisors (568072440).

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

216791640 is a wasteful number, since it uses less digits than its factorization.

216791640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5183 (or 5170 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 36.

The square root of 216791640 is about 14723.8459649645. The cubic root of 216791640 is about 600.7321063372.

The spelling of 216791640 in words is "two hundred sixteen million, seven hundred ninety-one thousand, six hundred forty".