991285 has 4 divisors (see below), whose sum is σ = 1189548. Its totient is φ = 793024.

The previous prime is 991273. The next prime is 991313. The reversal of 991285 is 582199.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 412164 + 579121 = 642^2 + 761^2 .

It is a cyclic number.

It is not a de Polignac number, because 991285 - 2¹⁹ = 466997 is a prime.

It is a Duffinian number.

991285 is a lucky number.

It is a plaindrome in base 15.

It is a self number, because there is not a number n which added to its sum of digits gives 991285.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 99124 + ... + 99133.

It is an arithmetic number, because the mean of its divisors is an integer number (297387).

2⁹⁹¹²⁸⁵ is an apocalyptic number.

It is an amenable number.

991285 is a deficient number, since it is larger than the sum of its proper divisors (198263).

991285 is a wasteful number, since it uses less digits than its factorization.

991285 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 198262.

The product of its digits is 6480, while the sum is 34.

The square root of 991285 is about 995.6329645005. The cubic root of 991285 is about 99.7086519877.

The spelling of 991285 in words is "nine hundred ninety-one thousand, two hundred eighty-five".