161997757 has 2 divisors, whose sum is σ = 161997758. Its totient is φ = 161997756.

The previous prime is 161997751. The next prime is 161997769. The reversal of 161997757 is 757799161.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 134235396 + 27762361 = 11586^2 + 5269^2 .

It is a cyclic number.

It is not a de Polignac number, because 161997757 - 2³ = 161997749 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161997751) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80998878 + 80998879.

It is an arithmetic number, because the mean of its divisors is an integer number (80998879).

Almost surely, 2^161997757 is an apocalyptic number.

It is an amenable number.

161997757 is a deficient number, since it is larger than the sum of its proper divisors (1).

161997757 is an equidigital number, since it uses as much as digits as its factorization.

161997757 is an evil number, because the sum of its binary digits is even.

The product of its digits is 833490, while the sum is 52.

The square root of 161997757 is about 12727.8339476912. The cubic root of 161997757 is about 545.1336619112.

The spelling of 161997757 in words is "one hundred sixty-one million, nine hundred ninety-seven thousand, seven hundred fifty-seven".