17181991997 has 2 divisors, whose sum is σ = 17181991998. Its totient is φ = 17181991996.

The previous prime is 17181991991. The next prime is 17181992117. The reversal of 17181991997 is 79919918171.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 9586172281 + 7595819716 = 97909^2 + 87154^2 .

It is a cyclic number.

It is not a de Polignac number, because 17181991997 - 2²⁰ = 17180943421 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (17181991991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8590995998 + 8590995999.

It is an arithmetic number, because the mean of its divisors is an integer number (8590995999).

Almost surely, 2^17181991997 is an apocalyptic number.

It is an amenable number.

17181991997 is a deficient number, since it is larger than the sum of its proper divisors (1).

17181991997 is an equidigital number, since it uses as much as digits as its factorization.

17181991997 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2571912, while the sum is 62.

The spelling of 17181991997 in words is "seventeen billion, one hundred eighty-one million, nine hundred ninety-one thousand, nine hundred ninety-seven".