161783561 has 2 divisors, whose sum is σ = 161783562. Its totient is φ = 161783560.

The previous prime is 161783533. The next prime is 161783591. The reversal of 161783561 is 165387161.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 149915536 + 11868025 = 12244^2 + 3445^2 .

It is a cyclic number.

It is not a de Polignac number, because 161783561 - 2⁶ = 161783497 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (161783591) 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, 80891780 + 80891781.

It is an arithmetic number, because the mean of its divisors is an integer number (80891781).

Almost surely, 2^161783561 is an apocalyptic number.

It is an amenable number.

161783561 is a deficient number, since it is larger than the sum of its proper divisors (1).

161783561 is an equidigital number, since it uses as much as digits as its factorization.

161783561 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 161783561 is about 12719.4166926003. The cubic root of 161783561 is about 544.8932944870.

The spelling of 161783561 in words is "one hundred sixty-one million, seven hundred eighty-three thousand, five hundred sixty-one".