161665567 has 4 divisors (see below), whose sum is σ = 184760656. Its totient is φ = 138570480.

The previous prime is 161665561. The next prime is 161665579. The reversal of 161665567 is 765566161.

161665567 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-161665567 is a prime.

It is a super-2 number, since 2×161665567² = 52271511106862978, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161665561) 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, 11547534 + ... + 11547547.

It is an arithmetic number, because the mean of its divisors is an integer number (46190164).

Almost surely, 2^161665567 is an apocalyptic number.

161665567 is a deficient number, since it is larger than the sum of its proper divisors (23095089).

161665567 is an equidigital number, since it uses as much as digits as its factorization.

161665567 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23095088.

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

The square root of 161665567 is about 12714.7775049350. Note that the first 3 decimals coincide. The cubic root of 161665567 is about 544.7607928164.

The spelling of 161665567 in words is "one hundred sixty-one million, six hundred sixty-five thousand, five hundred sixty-seven".