991381262291 has 12 divisors (see below), whose sum is σ = 1163445092712. Its totient is φ = 842235403968.

The previous prime is 991381262269. The next prime is 991381262303. The reversal of 991381262291 is 192262183199.

It is a happy number.

It is a de Polignac number, because none of the positive numbers 2^k-991381262291 is a prime.

It is not an unprimeable number, because it can be changed into a prime (991381262251) 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, 89517785 + ... + 89528858.

It is an arithmetic number, because the mean of its divisors is an integer number (96953757726).

Almost surely, 2^991381262291 is an apocalyptic number.

991381262291 is a deficient number, since it is larger than the sum of its proper divisors (172063830421).

991381262291 is a wasteful number, since it uses less digits than its factorization.

991381262291 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 179046770 (or 179046763 counting only the distinct ones).

The product of its digits is 839808, while the sum is 53.

The spelling of 991381262291 in words is "nine hundred ninety-one billion, three hundred eighty-one million, two hundred sixty-two thousand, two hundred ninety-one".