971599991 has 2 divisors, whose sum is σ = 971599992. Its totient is φ = 971599990.

The previous prime is 971599969. The next prime is 971599999. The reversal of 971599991 is 199995179.

It is a strong prime.

It is an emirp because it is prime and its reverse (199995179) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 971599991 - 2²⁶ = 904491127 is a prime.

It is a super-2 number, since 2×971599991² = 1888013085022400162, which contains 22 as substring.

It is a Sophie Germain prime.

It is a self number, because there is not a number n which added to its sum of digits gives 971599991.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (971599999) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 485799995 + 485799996.

It is an arithmetic number, because the mean of its divisors is an integer number (485799996).

Almost surely, 2^971599991 is an apocalyptic number.

971599991 is a deficient number, since it is larger than the sum of its proper divisors (1).

971599991 is an equidigital number, since it uses as much as digits as its factorization.

971599991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2066715, while the sum is 59.

The square root of 971599991 is about 31170.4987287660. The cubic root of 971599991 is about 990.4422711867.

The spelling of 971599991 in words is "nine hundred seventy-one million, five hundred ninety-nine thousand, nine hundred ninety-one".