991118407 has 2 divisors, whose sum is σ = 991118408. Its totient is φ = 991118406.

The previous prime is 991118357. The next prime is 991118419. The reversal of 991118407 is 704811199.

It is a strong prime.

It is an emirp because it is prime and its reverse (704811199) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-991118407 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 991118407.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (991118467) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495559203 + 495559204.

It is an arithmetic number, because the mean of its divisors is an integer number (495559204).

Almost surely, 2^991118407 is an apocalyptic number.

991118407 is a deficient number, since it is larger than the sum of its proper divisors (1).

991118407 is an equidigital number, since it uses as much as digits as its factorization.

991118407 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 18144, while the sum is 40.

The square root of 991118407 is about 31482.0330823789. The cubic root of 991118407 is about 997.0306607513.

The spelling of 991118407 in words is "nine hundred ninety-one million, one hundred eighteen thousand, four hundred seven".