165646561 has 4 divisors (see below), whose sum is σ = 165675952. Its totient is φ = 165617172.

The previous prime is 165646531. The next prime is 165646573.

165646561 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 165646561 - 2⁷ = 165646433 is a prime.

It is a super-2 number, since 2×165646561² = 54877566342253442, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (165646511) 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, 3291 + ... + 18496.

It is an arithmetic number, because the mean of its divisors is an integer number (41418988).

Almost surely, 2^165646561 is an apocalyptic number.

It is an amenable number.

165646561 is a deficient number, since it is larger than the sum of its proper divisors (29391).

165646561 is an equidigital number, since it uses as much as digits as its factorization.

165646561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29390.

The product of its digits is 129600, while the sum is 40.

The square root of 165646561 is about 12870.3753247526. The cubic root of 165646561 is about 549.1961380709.

The spelling of 165646561 in words is "one hundred sixty-five million, six hundred forty-six thousand, five hundred sixty-one".