991515 has 48 divisors (see below), whose sum is σ = 1969920. Its totient is φ = 423360.

The previous prime is 991511. The next prime is 991531. The reversal of 991515 is 515199.

991515 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 991515 - 2² = 991511 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991511) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 13930 + ... + 14000.

It is an arithmetic number, because the mean of its divisors is an integer number (41040).

2⁹⁹¹⁵¹⁵ is an apocalyptic number.

991515 is a gapful number since it is divisible by the number (95) formed by its first and last digit.

991515 is a deficient number, since it is larger than the sum of its proper divisors (978405).

991515 is a wasteful number, since it uses less digits than its factorization.

991515 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 112 (or 105 counting only the distinct ones).

The product of its digits is 2025, while the sum is 30.

The square root of 991515 is about 995.7484622132. The cubic root of 991515 is about 99.7163629274.

The spelling of 991515 in words is "nine hundred ninety-one thousand, five hundred fifteen".