991867979 has 2 divisors, whose sum is σ = 991867980. Its totient is φ = 991867978.

The previous prime is 991867949. The next prime is 991868041. The reversal of 991867979 is 979768199.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 991867979 - 2¹² = 991863883 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (991867949) 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 as a sum of consecutive naturals, namely, 495933989 + 495933990.

It is an arithmetic number, because the mean of its divisors is an integer number (495933990).

Almost surely, 2^991867979 is an apocalyptic number.

991867979 is a deficient number, since it is larger than the sum of its proper divisors (1).

991867979 is an equidigital number, since it uses as much as digits as its factorization.

991867979 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 15431472, while the sum is 65.

The square root of 991867979 is about 31493.9355908403. The cubic root of 991867979 is about 997.2819452050.

The spelling of 991867979 in words is "nine hundred ninety-one million, eight hundred sixty-seven thousand, nine hundred seventy-nine".