165618780161 has 2 divisors, whose sum is σ = 165618780162. Its totient is φ = 165618780160.

The previous prime is 165618780133. The next prime is 165618780193. The reversal of 165618780161 is 161087816561.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 135924942400 + 29693837761 = 368680^2 + 172319^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-165618780161 is a prime.

It is not a weakly prime, because it can be changed into another prime (165618780661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82809390080 + 82809390081.

It is an arithmetic number, because the mean of its divisors is an integer number (82809390081).

Almost surely, 2^165618780161 is an apocalyptic number.

It is an amenable number.

165618780161 is a deficient number, since it is larger than the sum of its proper divisors (1).

165618780161 is an equidigital number, since it uses as much as digits as its factorization.

165618780161 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 483840, while the sum is 50.

The spelling of 165618780161 in words is "one hundred sixty-five billion, six hundred eighteen million, seven hundred eighty thousand, one hundred sixty-one".