216979831 has 4 divisors (see below), whose sum is σ = 222272064. Its totient is φ = 211687600.

The previous prime is 216979813. The next prime is 216979853. The reversal of 216979831 is 138979612.

It is a happy number.

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 216979831 - 2⁵ = 216979799 is a prime.

It is a super-2 number, since 2×216979831² = 94160494121577122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216979801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2646055 + ... + 2646136.

It is an arithmetic number, because the mean of its divisors is an integer number (55568016).

Almost surely, 2^216979831 is an apocalyptic number.

216979831 is a deficient number, since it is larger than the sum of its proper divisors (5292233).

216979831 is an equidigital number, since it uses as much as digits as its factorization.

216979831 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5292232.

The product of its digits is 163296, while the sum is 46.

The square root of 216979831 is about 14730.2352662814. The cubic root of 216979831 is about 600.9058825323.

The spelling of 216979831 in words is "two hundred sixteen million, nine hundred seventy-nine thousand, eight hundred thirty-one".