161756813 has 2 divisors, whose sum is σ = 161756814. Its totient is φ = 161756812.

The previous prime is 161756797. The next prime is 161756839. The reversal of 161756813 is 318657161.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 145612489 + 16144324 = 12067^2 + 4018^2 .

It is an emirp because it is prime and its reverse (318657161) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 161756813 - 2⁴ = 161756797 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161756893) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80878406 + 80878407.

It is an arithmetic number, because the mean of its divisors is an integer number (80878407).

Almost surely, 2^161756813 is an apocalyptic number.

It is an amenable number.

161756813 is a deficient number, since it is larger than the sum of its proper divisors (1).

161756813 is an equidigital number, since it uses as much as digits as its factorization.

161756813 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 30240, while the sum is 38.

The square root of 161756813 is about 12718.3651858248. The cubic root of 161756813 is about 544.8632633988.

The spelling of 161756813 in words is "one hundred sixty-one million, seven hundred fifty-six thousand, eight hundred thirteen".