161377561 has 2 divisors, whose sum is σ = 161377562. Its totient is φ = 161377560.

The previous prime is 161377553. The next prime is 161377571. The reversal of 161377561 is 165773161.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 84989961 + 76387600 = 9219^2 + 8740^2 .

It is a cyclic number.

It is not a de Polignac number, because 161377561 - 2³ = 161377553 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 161377561.

It is not a weakly prime, because it can be changed into another prime (161377511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80688780 + 80688781.

It is an arithmetic number, because the mean of its divisors is an integer number (80688781).

Almost surely, 2^161377561 is an apocalyptic number.

It is an amenable number.

161377561 is a deficient number, since it is larger than the sum of its proper divisors (1).

161377561 is an equidigital number, since it uses as much as digits as its factorization.

161377561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 26460, while the sum is 37.

The square root of 161377561 is about 12703.4468157268. The cubic root of 161377561 is about 544.4371047632.

The spelling of 161377561 in words is "one hundred sixty-one million, three hundred seventy-seven thousand, five hundred sixty-one".