997959691 has 2 divisors, whose sum is σ = 997959692. Its totient is φ = 997959690.

The previous prime is 997959647. The next prime is 997959731. The reversal of 997959691 is 196959799.

It is a strong prime.

It is an emirp because it is prime and its reverse (196959799) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 997959691 - 2¹¹ = 997957643 is a prime.

It is the 31591-st Hogben number.

It is not a weakly prime, because it can be changed into another prime (997959191) by changing a digit.

It is a nontrivial repunit in base 31590.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 498979845 + 498979846.

It is an arithmetic number, because the mean of its divisors is an integer number (498979846).

Almost surely, 2^997959691 is an apocalyptic number.

997959691 is a deficient number, since it is larger than the sum of its proper divisors (1).

997959691 is an equidigital number, since it uses as much as digits as its factorization.

997959691 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12400290, while the sum is 64.

The square root of 997959691 is about 31590.5000118707. The cubic root of 997959691 is about 999.3194339349.

The spelling of 997959691 in words is "nine hundred ninety-seven million, nine hundred fifty-nine thousand, six hundred ninety-one".