991098965 has 4 divisors (see below), whose sum is σ = 1189318764. Its totient is φ = 792879168.

The previous prime is 991098943. The next prime is 991098967. The reversal of 991098965 is 569890199.

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

It can be written as a sum of positive squares in 2 ways, for example, as 599613169 + 391485796 = 24487^2 + 19786^2 .

It is a cyclic number.

It is not a de Polignac number, because 991098965 - 2¹⁰ = 991097941 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 991098965.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991098967) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 99109892 + ... + 99109901.

It is an arithmetic number, because the mean of its divisors is an integer number (297329691).

Almost surely, 2^991098965 is an apocalyptic number.

It is an amenable number.

991098965 is a deficient number, since it is larger than the sum of its proper divisors (198219799).

991098965 is a wasteful number, since it uses less digits than its factorization.

991098965 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 198219798.

The product of its (nonzero) digits is 1574640, while the sum is 56.

The square root of 991098965 is about 31481.7243015690. The cubic root of 991098965 is about 997.0241413833.

The spelling of 991098965 in words is "nine hundred ninety-one million, ninety-eight thousand, nine hundred sixty-five".