991362665 has 4 divisors (see below), whose sum is σ = 1189635204. Its totient is φ = 793090128.

The previous prime is 991362649. The next prime is 991362683. The reversal of 991362665 is 566263199.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 566263199 = 2791 ⋅202889.

It can be written as a sum of positive squares in 2 ways, for example, as 367412224 + 623950441 = 19168^2 + 24979^2 .

It is a cyclic number.

It is not a de Polignac number, because 991362665 - 2⁴ = 991362649 is a prime.

It is a Duffinian number.

It is an unprimeable number.

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, 99136262 + ... + 99136271.

It is an arithmetic number, because the mean of its divisors is an integer number (297408801).

Almost surely, 2^991362665 is an apocalyptic number.

It is an amenable number.

991362665 is a deficient number, since it is larger than the sum of its proper divisors (198272539).

991362665 is a wasteful number, since it uses less digits than its factorization.

991362665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 198272538.

The product of its digits is 524880, while the sum is 47.

The square root of 991362665 is about 31485.9121671899. The cubic root of 991362665 is about 997.1125590426.

The spelling of 991362665 in words is "nine hundred ninety-one million, three hundred sixty-two thousand, six hundred sixty-five".