161688265 has 8 divisors (see below), whose sum is σ = 194157000. Its totient is φ = 129263232.

The previous prime is 161688257. The next prime is 161688269. The reversal of 161688265 is 562886161.

It can be written as a sum of positive squares in 4 ways, for example, as 499849 + 161188416 = 707^2 + 12696^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 161688265 - 2³ = 161688257 is a prime.

It is a super-2 number, since 2×161688265² = 52286190077420450, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (161688269) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2140 + ... + 18109.

It is an arithmetic number, because the mean of its divisors is an integer number (24269625).

Almost surely, 2^161688265 is an apocalyptic number.

It is an amenable number.

161688265 is a deficient number, since it is larger than the sum of its proper divisors (32468735).

161688265 is a wasteful number, since it uses less digits than its factorization.

161688265 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21851.

The product of its digits is 138240, while the sum is 43.

The square root of 161688265 is about 12715.6700570595. The cubic root of 161688265 is about 544.7862866018.

The spelling of 161688265 in words is "one hundred sixty-one million, six hundred eighty-eight thousand, two hundred sixty-five".