991765 has 8 divisors (see below), whose sum is σ = 1199520. Its totient is φ = 787152.

The previous prime is 991751. The next prime is 991777. The reversal of 991765 is 567199.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 991765 - 2⁵ = 991733 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19 + ... + 1408.

It is an arithmetic number, because the mean of its divisors is an integer number (149940).

2⁹⁹¹⁷⁶⁵ is an apocalyptic number.

It is an amenable number.

991765 is a deficient number, since it is larger than the sum of its proper divisors (207755).

991765 is a wasteful number, since it uses less digits than its factorization.

991765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1571.

The product of its digits is 17010, while the sum is 37.

The square root of 991765 is about 995.8739880125. The cubic root of 991765 is about 99.7247430312.

The spelling of 991765 in words is "nine hundred ninety-one thousand, seven hundred sixty-five".