991610791 has 2 divisors, whose sum is σ = 991610792. Its totient is φ = 991610790.

The previous prime is 991610783. The next prime is 991610801. The reversal of 991610791 is 197016199.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 991610791 - 2³ = 991610783 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (991610771) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495805395 + 495805396.

It is an arithmetic number, because the mean of its divisors is an integer number (495805396).

Almost surely, 2^991610791 is an apocalyptic number.

991610791 is a deficient number, since it is larger than the sum of its proper divisors (1).

991610791 is an equidigital number, since it uses as much as digits as its factorization.

991610791 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 30618, while the sum is 43.

The square root of 991610791 is about 31489.8521908249. The cubic root of 991610791 is about 997.1957404793.

The spelling of 991610791 in words is "nine hundred ninety-one million, six hundred ten thousand, seven hundred ninety-one".