991860 has 48 divisors (see below), whose sum is σ = 2833152. Its totient is φ = 259200.

The previous prime is 991817. The next prime is 991867. The reversal of 991860 is 68199.

It is a happy number.

991860 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 not an unprimeable number, because it can be changed into a prime (991867) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3525 + ... + 3795.

It is an arithmetic number, because the mean of its divisors is an integer number (59024).

2⁹⁹¹⁸⁶⁰ 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 991860, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1416576).

991860 is an abundant number, since it is smaller than the sum of its proper divisors (1841292).

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

991860 is a wasteful number, since it uses less digits than its factorization.

991860 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 344 (or 342 counting only the distinct ones).

The product of its (nonzero) digits is 3888, while the sum is 33.

The square root of 991860 is about 995.9216836679. The cubic root of 991860 is about 99.7279271014.

The spelling of 991860 in words is "nine hundred ninety-one thousand, eight hundred sixty".