1991115 has 64 divisors (see below), whose sum is σ = 4224000. Its totient is φ = 889056.

The previous prime is 1991107. The next prime is 1991123. The reversal of 1991115 is 5111991.

It is an interprime number because it is at equal distance from previous prime (1991107) and next prime (1991123).

It is not a de Polignac number, because 1991115 - 2³ = 1991107 is a prime.

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

It is a nude number because it is divisible by every one of its digits.

1991115 is a lucky number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 46284 + ... + 46326.

It is an arithmetic number, because the mean of its divisors is an integer number (66000).

2^1991115 is an apocalyptic number.

1991115 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

1991115 is an abundant number, since it is smaller than the sum of its proper divisors (2232885).

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

1991115 is an equidigital number, since it uses as much as digits as its factorization.

1991115 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78 (or 58 counting only the distinct ones).

The product of its digits is 405, while the sum is 27.

The square root of 1991115 is about 1411.0687438959. The cubic root of 1991115 is about 125.8052547128.

The spelling of 1991115 in words is "one million, nine hundred ninety-one thousand, one hundred fifteen".