991280791 has 4 divisors (see below), whose sum is σ = 991406592. Its totient is φ = 991154992.

The previous prime is 991280779. The next prime is 991280839. The reversal of 991280791 is 197082199.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 991280791 - 2²¹ = 989183639 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991280891) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 50230 + ... + 67123.

It is an arithmetic number, because the mean of its divisors is an integer number (247851648).

Almost surely, 2^991280791 is an apocalyptic number.

991280791 is a deficient number, since it is larger than the sum of its proper divisors (125801).

991280791 is a wasteful number, since it uses less digits than its factorization.

991280791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 125800.

The product of its (nonzero) digits is 81648, while the sum is 46.

The square root of 991280791 is about 31484.6119715648. The cubic root of 991280791 is about 997.0851086640.

The spelling of 991280791 in words is "nine hundred ninety-one million, two hundred eighty thousand, seven hundred ninety-one".