991305 has 32 divisors (see below), whose sum is σ = 2016000. Its totient is φ = 452736.

The previous prime is 991273. The next prime is 991313. The reversal of 991305 is 503199.

It is not a de Polignac number, because 991305 - 2⁵ = 991273 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Curzon number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 991305.

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, 421 + ... + 1469.

It is an arithmetic number, because the mean of its divisors is an integer number (63000).

2⁹⁹¹³⁰⁵ is an apocalyptic number.

991305 is the 630-th heptagonal number.

It is an amenable number.

991305 is an abundant number, since it is smaller than the sum of its proper divisors (1024695).

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

991305 is a wasteful number, since it uses less digits than its factorization.

991305 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1070 (or 1064 counting only the distinct ones).

The product of its (nonzero) digits is 1215, while the sum is 27.

The square root of 991305 is about 995.6430083117. The cubic root of 991305 is about 99.7093225516.

It can be divided in two parts, 991 and 305, that added together give a 4-th power (1296 = 6⁴).

The spelling of 991305 in words is "nine hundred ninety-one thousand, three hundred five".