165868561 has 4 divisors (see below), whose sum is σ = 167062000. Its totient is φ = 164675124.

The previous prime is 165868559. The next prime is 165868579.

165868561 is nontrivially palindromic in base 10.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 165868561 - 2¹ = 165868559 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (165868061) 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 in 3 ways as a sum of consecutive naturals, for example, 596511 + ... + 596788.

It is an arithmetic number, because the mean of its divisors is an integer number (41765500).

Almost surely, 2^165868561 is an apocalyptic number.

It is an amenable number.

165868561 is a deficient number, since it is larger than the sum of its proper divisors (1193439).

165868561 is a wasteful number, since it uses less digits than its factorization.

165868561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1193438.

The product of its digits is 345600, while the sum is 46.

The square root of 165868561 is about 12878.9968941684. The cubic root of 165868561 is about 549.4413732993.

The spelling of 165868561 in words is "one hundred sixty-five million, eight hundred sixty-eight thousand, five hundred sixty-one".