991002497 has 2 divisors, whose sum is σ = 991002498. Its totient is φ = 991002496.

The previous prime is 991002457. The next prime is 991002499. The reversal of 991002497 is 794200199.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 571735921 + 419266576 = 23911^2 + 20476^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-991002497 is a prime.

Together with 991002499, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (991002499) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495501248 + 495501249.

It is an arithmetic number, because the mean of its divisors is an integer number (495501249).

Almost surely, 2^991002497 is an apocalyptic number.

It is an amenable number.

991002497 is a deficient number, since it is larger than the sum of its proper divisors (1).

991002497 is an equidigital number, since it uses as much as digits as its factorization.

991002497 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 40824, while the sum is 41.

The square root of 991002497 is about 31480.1921372790. The cubic root of 991002497 is about 996.9917920926.

The spelling of 991002497 in words is "nine hundred ninety-one million, two thousand, four hundred ninety-seven".