161817973 has 2 divisors, whose sum is σ = 161817974. Its totient is φ = 161817972.

The previous prime is 161817947. The next prime is 161817989. The reversal of 161817973 is 379718161.

It is a happy number.

161817973 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 147695409 + 14122564 = 12153^2 + 3758^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-161817973 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161814973) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80908986 + 80908987.

It is an arithmetic number, because the mean of its divisors is an integer number (80908987).

Almost surely, 2^161817973 is an apocalyptic number.

It is an amenable number.

161817973 is a deficient number, since it is larger than the sum of its proper divisors (1).

161817973 is an equidigital number, since it uses as much as digits as its factorization.

161817973 is an evil number, because the sum of its binary digits is even.

The product of its digits is 63504, while the sum is 43.

The square root of 161817973 is about 12720.7693556640. The cubic root of 161817973 is about 544.9319253974.

It can be divided in two parts, 1618 and 17973, that added together give a palindrome (19591).

The spelling of 161817973 in words is "one hundred sixty-one million, eight hundred seventeen thousand, nine hundred seventy-three".