991871199365 has 16 divisors (see below), whose sum is σ = 1307363414400. Its totient is φ = 719049874752.

The previous prime is 991871199359. The next prime is 991871199383. The reversal of 991871199365 is 563991178199.

It is a cyclic number.

It is not a de Polignac number, because 991871199365 - 2²⁴ = 991854422149 is a prime.

It is a super-2 number, since 2×991871199365² (a number of 25 digits) contains 22 as substring.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 991871199295 and 991871199304.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 226970630 + ... + 226974999.

It is an arithmetic number, because the mean of its divisors is an integer number (81710213400).

Almost surely, 2^991871199365 is an apocalyptic number.

991871199365 is a gapful number since it is divisible by the number (95) formed by its first and last digit.

It is an amenable number.

991871199365 is a deficient number, since it is larger than the sum of its proper divisors (315492215035).

991871199365 is a wasteful number, since it uses less digits than its factorization.

991871199365 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 453945676.

The product of its digits is 33067440, while the sum is 68.

The spelling of 991871199365 in words is "nine hundred ninety-one billion, eight hundred seventy-one million, one hundred ninety-nine thousand, three hundred sixty-five".