991761 has 4 divisors (see below), whose sum is σ = 1322352. Its totient is φ = 661172.

The previous prime is 991751. The next prime is 991777. The reversal of 991761 is 167199.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 167199 = 3 ⋅55733.

It is a cyclic number.

It is not a de Polignac number, because 991761 - 2⁷ = 991633 is a prime.

It is a super-2 number, since 2×991761² = 1967179762242, which contains 22 as substring.

It is a D-number.

It is a Curzon number.

991761 is a lucky number.

It is a nialpdrome in base 16.

It is not an unprimeable number, because it can be changed into a prime (991741) 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, 165291 + ... + 165296.

It is an arithmetic number, because the mean of its divisors is an integer number (330588).

2⁹⁹¹⁷⁶¹ is an apocalyptic number.

It is an amenable number.

991761 is a deficient number, since it is larger than the sum of its proper divisors (330591).

991761 is a wasteful number, since it uses less digits than its factorization.

991761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 330590.

The product of its digits is 3402, while the sum is 33.

The square root of 991761 is about 995.8719797243. The cubic root of 991761 is about 99.7246089606.

The spelling of 991761 in words is "nine hundred ninety-one thousand, seven hundred sixty-one".