161665868 has 48 divisors (see below), whose sum is σ = 359460864. Its totient is φ = 61888320.

The previous prime is 161665843. The next prime is 161665897. The reversal of 161665868 is 868566161.

It is a super-2 number, since 2×161665868² = 52271705752386848, which contains 22 as substring.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 4121 + ... + 18447.

It is an arithmetic number, because the mean of its divisors is an integer number (7488768).

Almost surely, 2^161665868 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 161665868, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (179730432).

161665868 is an abundant number, since it is smaller than the sum of its proper divisors (197794996).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

161665868 is a wasteful number, since it uses less digits than its factorization.

161665868 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14382 (or 14380 counting only the distinct ones).

The product of its digits is 414720, while the sum is 47.

The square root of 161665868 is about 12714.7893415503. The cubic root of 161665868 is about 544.7611309071.

The spelling of 161665868 in words is "one hundred sixty-one million, six hundred sixty-five thousand, eight hundred sixty-eight".