991890279 has 24 divisors (see below), whose sum is σ = 1573200720. Its totient is φ = 622359936.

The previous prime is 991890271. The next prime is 991890301. The reversal of 991890279 is 972098199.

It is not a de Polignac number, because 991890279 - 2³ = 991890271 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991890271) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 115924 + ... + 124185.

It is an arithmetic number, because the mean of its divisors is an integer number (65550030).

Almost surely, 2^991890279 is an apocalyptic number.

991890279 is a deficient number, since it is larger than the sum of its proper divisors (581310441).

991890279 is a wasteful number, since it uses less digits than its factorization.

991890279 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 240141 (or 240129 counting only the distinct ones).

The product of its (nonzero) digits is 734832, while the sum is 54.

The square root of 991890279 is about 31494.2896252638. The cubic root of 991890279 is about 997.2894190561.

The spelling of 991890279 in words is "nine hundred ninety-one million, eight hundred ninety thousand, two hundred seventy-nine".