165566761 has 4 divisors (see below), whose sum is σ = 166582672. Its totient is φ = 164550852.

The previous prime is 165566743. The next prime is 165566773. The reversal of 165566761 is 167665561.

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 a de Polignac number, because none of the positive numbers 2^k-165566761 is a prime.

It is a super-2 number, since 2×165566761² = 54824704696062242, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (165566711) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 507711 + ... + 508036.

It is an arithmetic number, because the mean of its divisors is an integer number (41645668).

Almost surely, 2^165566761 is an apocalyptic number.

It is an amenable number.

165566761 is a deficient number, since it is larger than the sum of its proper divisors (1015911).

165566761 is a wasteful number, since it uses less digits than its factorization.

165566761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1015910.

The product of its digits is 226800, while the sum is 43.

The square root of 165566761 is about 12867.2748085988. The cubic root of 165566761 is about 549.1079324136.

The spelling of 165566761 in words is "one hundred sixty-five million, five hundred sixty-six thousand, seven hundred sixty-one".