161285665 has 8 divisors (see below), whose sum is σ = 195319080. Its totient is φ = 127844352.

The previous prime is 161285639. The next prime is 161285693. The reversal of 161285665 is 566582161.

It can be written as a sum of positive squares in 4 ways, for example, as 85229824 + 76055841 = 9232^2 + 8721^2 .

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

It is a 3-Lehmer number, since φ(161285665) divides (161285665-1)³.

It is a cyclic number.

It is not a de Polignac number, because 161285665 - 2⁵ = 161285633 is a prime.

It is an unprimeable number.

It is a nontrivial repunit in base 544.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 147424 + ... + 148513.

It is an arithmetic number, because the mean of its divisors is an integer number (24414885).

Almost surely, 2^161285665 is an apocalyptic number.

It is an amenable number.

161285665 is a deficient number, since it is larger than the sum of its proper divisors (34033415).

161285665 is a wasteful number, since it uses less digits than its factorization.

161285665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 296051.

The product of its digits is 86400, while the sum is 40.

The square root of 161285665 is about 12699.8293295619. The cubic root of 161285665 is about 544.3337424129. Note that the first 3 decimals are identical.

The spelling of 161285665 in words is "one hundred sixty-one million, two hundred eighty-five thousand, six hundred sixty-five".