216511640 has 16 divisors (see below), whose sum is σ = 487151280. Its totient is φ = 86604640.

The previous prime is 216511637. The next prime is 216511667. The reversal of 216511640 is 46115612.

216511640 is digitally balanced in base 3, 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 3 ways as a sum of consecutive naturals, for example, 2706356 + ... + 2706435.

It is an arithmetic number, because the mean of its divisors is an integer number (30446955).

Almost surely, 2^216511640 is an apocalyptic number.

216511640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

216511640 is an abundant number, since it is smaller than the sum of its proper divisors (270639640).

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

216511640 is a wasteful number, since it uses less digits than its factorization.

216511640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5412802 (or 5412798 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 26.

The square root of 216511640 is about 14714.3345075474. The cubic root of 216511640 is about 600.4733671817.

The spelling of 216511640 in words is "two hundred sixteen million, five hundred eleven thousand, six hundred forty".