991172 has 36 divisors (see below), whose sum is σ = 2178540. Its totient is φ = 391104.

The previous prime is 991171. The next prime is 991181. The reversal of 991172 is 271199.

It can be written as a sum of positive squares in 2 ways, for example, as 188356 + 802816 = 434^2 + 896^2 .

It is not an unprimeable number, because it can be changed into a prime (991171) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2354 + ... + 2742.

It is an arithmetic number, because the mean of its divisors is an integer number (60515).

2⁹⁹¹¹⁷² is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 991172, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1089270).

991172 is an abundant number, since it is smaller than the sum of its proper divisors (1187368).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

991172 is a wasteful number, since it uses less digits than its factorization.

991172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 420 (or 411 counting only the distinct ones).

The product of its digits is 1134, while the sum is 29.

The square root of 991172 is about 995.5762150634. The cubic root of 991172 is about 99.7048631326.

The spelling of 991172 in words is "nine hundred ninety-one thousand, one hundred seventy-two".