991506 has 16 divisors (see below), whose sum is σ = 1993824. Its totient is φ = 328704.

The previous prime is 991499. The next prime is 991511. The reversal of 991506 is 605199.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1221 + ... + 1863.

It is an arithmetic number, because the mean of its divisors is an integer number (124614).

2⁹⁹¹⁵⁰⁶ is an apocalyptic number.

991506 is an abundant number, since it is smaller than the sum of its proper divisors (1002318).

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

991506 is a wasteful number, since it uses less digits than its factorization.

991506 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 905.

The product of its (nonzero) digits is 2430, while the sum is 30.

The square root of 991506 is about 995.7439429894. The cubic root of 991506 is about 99.7160612174.

The spelling of 991506 in words is "nine hundred ninety-one thousand, five hundred six".