991115 has 4 divisors (see below), whose sum is σ = 1189344. Its totient is φ = 792888.

The previous prime is 991091. The next prime is 991127. The reversal of 991115 is 511199.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 511199 = 13 ⋅39323.

It is a cyclic number.

It is not a de Polignac number, because 991115 - 2¹⁶ = 925579 is a prime.

It is a super-3 number, since 3×991115³ = 2920743384793337625, which contains 333 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 99107 + ... + 99116.

It is an arithmetic number, because the mean of its divisors is an integer number (297336).

2⁹⁹¹¹¹⁵ is an apocalyptic number.

991115 is a deficient number, since it is larger than the sum of its proper divisors (198229).

991115 is a wasteful number, since it uses less digits than its factorization.

991115 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 198228.

The product of its digits is 405, while the sum is 26.

The square root of 991115 is about 995.5475880138. The cubic root of 991115 is about 99.7029518309.

The spelling of 991115 in words is "nine hundred ninety-one thousand, one hundred fifteen".