216879791 has 4 divisors (see below), whose sum is σ = 222169584. Its totient is φ = 211590000.

The previous prime is 216879779. The next prime is 216879797. The reversal of 216879791 is 197978612.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-216879791 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216879797) 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 3 ways as a sum of consecutive naturals, for example, 2644835 + ... + 2644916.

It is an arithmetic number, because the mean of its divisors is an integer number (55542396).

Almost surely, 2^216879791 is an apocalyptic number.

216879791 is a deficient number, since it is larger than the sum of its proper divisors (5289793).

216879791 is an equidigital number, since it uses as much as digits as its factorization.

216879791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5289792.

The product of its digits is 381024, while the sum is 50.

The square root of 216879791 is about 14726.8391381179. The cubic root of 216879791 is about 600.8135177792.

The spelling of 216879791 in words is "two hundred sixteen million, eight hundred seventy-nine thousand, seven hundred ninety-one".