161965920709 has 2 divisors, whose sum is σ = 161965920710. Its totient is φ = 161965920708.

The previous prime is 161965920653. The next prime is 161965920749. The reversal of 161965920709 is 907029569161.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 101930140225 + 60035780484 = 319265^2 + 245022^2 .

It is a cyclic number.

It is not a de Polignac number, because 161965920709 - 2¹¹ = 161965918661 is a prime.

It is a super-2 number, since 2×161965920709² (a number of 23 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 161965920709.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161965920749) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80982960354 + 80982960355.

It is an arithmetic number, because the mean of its divisors is an integer number (80982960355).

Almost surely, 2^161965920709 is an apocalyptic number.

It is an amenable number.

161965920709 is a deficient number, since it is larger than the sum of its proper divisors (1).

161965920709 is an equidigital number, since it uses as much as digits as its factorization.

161965920709 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1837080, while the sum is 55.

The spelling of 161965920709 in words is "one hundred sixty-one billion, nine hundred sixty-five million, nine hundred twenty thousand, seven hundred nine".