216640615 has 4 divisors (see below), whose sum is σ = 259968744. Its totient is φ = 173312488.

The previous prime is 216640609. The next prime is 216640631. The reversal of 216640615 is 516046612.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 216640615 - 2¹⁷ = 216509543 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

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, 21664057 + ... + 21664066.

It is an arithmetic number, because the mean of its divisors is an integer number (64992186).

Almost surely, 2^216640615 is an apocalyptic number.

216640615 is a deficient number, since it is larger than the sum of its proper divisors (43328129).

216640615 is an equidigital number, since it uses as much as digits as its factorization.

216640615 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43328128.

The product of its (nonzero) digits is 8640, while the sum is 31.

The square root of 216640615 is about 14718.7164861614. The cubic root of 216640615 is about 600.5925765993.

The spelling of 216640615 in words is "two hundred sixteen million, six hundred forty thousand, six hundred fifteen".