165643531 has 4 divisors (see below), whose sum is σ = 165837672. Its totient is φ = 165449392.

The previous prime is 165643523. The next prime is 165643607. The reversal of 165643531 is 135346561.

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 165643531 - 2³ = 165643523 is a prime.

It is a super-2 number, since 2×165643531² = 54875558724295922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (165646531) 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, 95785 + ... + 97498.

It is an arithmetic number, because the mean of its divisors is an integer number (41459418).

Almost surely, 2^165643531 is an apocalyptic number.

165643531 is a deficient number, since it is larger than the sum of its proper divisors (194141).

165643531 is an equidigital number, since it uses as much as digits as its factorization.

165643531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 194140.

The product of its digits is 32400, while the sum is 34.

The square root of 165643531 is about 12870.2576120294. The cubic root of 165643531 is about 549.1927894262.

The spelling of 165643531 in words is "one hundred sixty-five million, six hundred forty-three thousand, five hundred thirty-one".