991755 has 12 divisors (see below), whose sum is σ = 1719120. Its totient is φ = 528912.

The previous prime is 991751. The next prime is 991777. The reversal of 991755 is 557199.

It is a happy number.

It is not a de Polignac number, because 991755 - 2² = 991751 is a prime.

It is not an unprimeable number, because it can be changed into a prime (991751) 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, 10975 + ... + 11064.

It is an arithmetic number, because the mean of its divisors is an integer number (143260).

2⁹⁹¹⁷⁵⁵ is an apocalyptic number.

991755 is a deficient number, since it is larger than the sum of its proper divisors (727365).

991755 is a wasteful number, since it uses less digits than its factorization.

991755 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22050 (or 22047 counting only the distinct ones).

The product of its digits is 14175, while the sum is 36.

The square root of 991755 is about 995.8689672844. The cubic root of 991755 is about 99.7244078541.

The spelling of 991755 in words is "nine hundred ninety-one thousand, seven hundred fifty-five".