991375 has 32 divisors (see below), whose sum is σ = 1557504. Its totient is φ = 612000.

The previous prime is 991357. The next prime is 991381. The reversal of 991375 is 573199.

991375 is nontrivially palindromic in base 4.

991375 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 991375 - 2⁵ = 991343 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 991375.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 9574 + ... + 9676.

It is an arithmetic number, because the mean of its divisors is an integer number (48672).

2⁹⁹¹³⁷⁵ is an apocalyptic number.

991375 is a deficient number, since it is larger than the sum of its proper divisors (566129).

991375 is a wasteful number, since it uses less digits than its factorization.

991375 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 136 (or 126 counting only the distinct ones).

The product of its digits is 8505, while the sum is 34.

The square root of 991375 is about 995.6781608532. The cubic root of 991375 is about 99.7116694540.

The spelling of 991375 in words is "nine hundred ninety-one thousand, three hundred seventy-five".