161818493 has 2 divisors, whose sum is σ = 161818494. Its totient is φ = 161818492.

The previous prime is 161818483. The next prime is 161818523. The reversal of 161818493 is 394818161.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 130256569 + 31561924 = 11413^2 + 5618^2 .

It is a cyclic number.

It is not a de Polignac number, because 161818493 - 2⁴ = 161818477 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 161818493.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161818403) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80909246 + 80909247.

It is an arithmetic number, because the mean of its divisors is an integer number (80909247).

Almost surely, 2^161818493 is an apocalyptic number.

It is an amenable number.

161818493 is a deficient number, since it is larger than the sum of its proper divisors (1).

161818493 is an equidigital number, since it uses as much as digits as its factorization.

161818493 is an evil number, because the sum of its binary digits is even.

The product of its digits is 41472, while the sum is 41.

The square root of 161818493 is about 12720.7897946629. The cubic root of 161818493 is about 544.9325091074.

The spelling of 161818493 in words is "one hundred sixty-one million, eight hundred eighteen thousand, four hundred ninety-three".