165644861 has 2 divisors, whose sum is σ = 165644862. Its totient is φ = 165644860.

The previous prime is 165644849. The next prime is 165644887. The reversal of 165644861 is 168446561.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 163993636 + 1651225 = 12806^2 + 1285^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-165644861 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (165604861) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82822430 + 82822431.

It is an arithmetic number, because the mean of its divisors is an integer number (82822431).

Almost surely, 2^165644861 is an apocalyptic number.

It is an amenable number.

165644861 is a deficient number, since it is larger than the sum of its proper divisors (1).

165644861 is an equidigital number, since it uses as much as digits as its factorization.

165644861 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 138240, while the sum is 41.

The square root of 165644861 is about 12870.3092814431. The cubic root of 165644861 is about 549.1942592984.

The spelling of 165644861 in words is "one hundred sixty-five million, six hundred forty-four thousand, eight hundred sixty-one".