991613 has 12 divisors (see below), whose sum is σ = 1176480. Its totient is φ = 835548.

The previous prime is 991607. The next prime is 991619. The reversal of 991613 is 316199.

It is an interprime number because it is at equal distance from previous prime (991607) and next prime (991619).

It is not a de Polignac number, because 991613 - 2⁸ = 991357 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 991613.

It is not an unprimeable number, because it can be changed into a prime (991619) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 16778 + ... + 16836.

It is an arithmetic number, because the mean of its divisors is an integer number (98040).

2⁹⁹¹⁶¹³ is an apocalyptic number.

It is an amenable number.

991613 is a deficient number, since it is larger than the sum of its proper divisors (184867).

991613 is an frugal number, since it uses more digits than its factorization.

991613 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 94 (or 66 counting only the distinct ones).

The product of its digits is 1458, while the sum is 29.

The square root of 991613 is about 995.7976702122. The cubic root of 991613 is about 99.7196480959.

The spelling of 991613 in words is "nine hundred ninety-one thousand, six hundred thirteen".