165561671 has 4 divisors (see below), whose sum is σ = 180612744. Its totient is φ = 150510600.

The previous prime is 165561661. The next prime is 165561679. The reversal of 165561671 is 176165561.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 165561671 - 2¹⁴ = 165545287 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165561679) 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, 7525520 + ... + 7525541.

It is an arithmetic number, because the mean of its divisors is an integer number (45153186).

Almost surely, 2^165561671 is an apocalyptic number.

165561671 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

165561671 is a deficient number, since it is larger than the sum of its proper divisors (15051073).

165561671 is a wasteful number, since it uses less digits than its factorization.

165561671 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15051072.

The product of its digits is 37800, while the sum is 38.

The square root of 165561671 is about 12867.0770184996. The cubic root of 165561671 is about 549.1023053018.

The spelling of 165561671 in words is "one hundred sixty-five million, five hundred sixty-one thousand, six hundred seventy-one".