165213661 has 2 divisors, whose sum is σ = 165213662. Its totient is φ = 165213660.

The previous prime is 165213647. The next prime is 165213689. The reversal of 165213661 is 166312561.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 159896025 + 5317636 = 12645^2 + 2306^2 .

It is a cyclic number.

It is not a de Polignac number, because 165213661 - 2⁷ = 165213533 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (165213691) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82606830 + 82606831.

It is an arithmetic number, because the mean of its divisors is an integer number (82606831).

Almost surely, 2^165213661 is an apocalyptic number.

It is an amenable number.

165213661 is a deficient number, since it is larger than the sum of its proper divisors (1).

165213661 is an equidigital number, since it uses as much as digits as its factorization.

165213661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6480, while the sum is 31.

The square root of 165213661 is about 12853.5466311832. The cubic root of 165213661 is about 548.7172984319.

The spelling of 165213661 in words is "one hundred sixty-five million, two hundred thirteen thousand, six hundred sixty-one".