991772 has 6 divisors (see below), whose sum is σ = 1735608. Its totient is φ = 495884.

The previous prime is 991751. The next prime is 991777. The reversal of 991772 is 277199.

It is a super-2 number, since 2×991772² = 1967223399968, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991777) by changing a digit.

991772 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 123968 + ... + 123975.

It is an arithmetic number, because the mean of its divisors is an integer number (289268).

2⁹⁹¹⁷⁷² is an apocalyptic number.

It is an amenable number.

991772 is a deficient number, since it is larger than the sum of its proper divisors (743836).

991772 is a wasteful number, since it uses less digits than its factorization.

991772 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 247947 (or 247945 counting only the distinct ones).

The product of its digits is 7938, while the sum is 35.

The square root of 991772 is about 995.8775025072. The cubic root of 991772 is about 99.7249776538.

The spelling of 991772 in words is "nine hundred ninety-one thousand, seven hundred seventy-two".