991956 has 48 divisors (see below), whose sum is σ = 2710400. Its totient is φ = 282240.

The previous prime is 991951. The next prime is 991957. The reversal of 991956 is 659199.

991956 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 991956.

It is not an unprimeable number, because it can be changed into a prime (991951) by changing a digit.

991956 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 in 15 ways as a sum of consecutive naturals, for example, 3996 + ... + 4236.

2⁹⁹¹⁹⁵⁶ 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 991956, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1355200).

991956 is an abundant number, since it is smaller than the sum of its proper divisors (1718444).

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

991956 is a wasteful number, since it uses less digits than its factorization.

991956 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 269 (or 253 counting only the distinct ones).

The product of its digits is 21870, while the sum is 39.

The square root of 991956 is about 995.9698790626. The cubic root of 991956 is about 99.7311444816.

The spelling of 991956 in words is "nine hundred ninety-one thousand, nine hundred fifty-six".