991131131199 has 32 divisors (see below), whose sum is σ = 1533172582656. Its totient is φ = 562860485120.

The previous prime is 991131131197. The next prime is 991131131209.

991131131199 is nontrivially palindromic in base 10.

It is a cyclic number.

It is not a de Polignac number, because 991131131199 - 2¹ = 991131131197 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991131131197) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3764112 + ... + 4018805.

It is an arithmetic number, because the mean of its divisors is an integer number (47911643208).

Almost surely, 2^991131131199 is an apocalyptic number.

991131131199 is a deficient number, since it is larger than the sum of its proper divisors (542041451457).

991131131199 is a wasteful number, since it uses less digits than its factorization.

991131131199 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7783175.

The product of its digits is 59049, while the sum is 48.

The spelling of 991131131199 in words is "nine hundred ninety-one billion, one hundred thirty-one million, one hundred thirty-one thousand, one hundred ninety-nine".