171663491 has 2 divisors, whose sum is σ = 171663492. Its totient is φ = 171663490.

The previous prime is 171663451. The next prime is 171663493. The reversal of 171663491 is 194366171.

It is a happy number.

It is a strong prime.

It is an emirp because it is prime and its reverse (194366171) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 171663491 - 2²⁶ = 104554627 is a prime.

It is a Sophie Germain prime.

Together with 171663493, 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 (171663493) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 85831745 + 85831746.

It is an arithmetic number, because the mean of its divisors is an integer number (85831746).

Almost surely, 2^171663491 is an apocalyptic number.

171663491 is a deficient number, since it is larger than the sum of its proper divisors (1).

171663491 is an equidigital number, since it uses as much as digits as its factorization.

171663491 is an evil number, because the sum of its binary digits is even.

The product of its digits is 27216, while the sum is 38.

The square root of 171663491 is about 13102.0414821508. The cubic root of 171663491 is about 555.7668602708.

The spelling of 171663491 in words is "one hundred seventy-one million, six hundred sixty-three thousand, four hundred ninety-one".