161668290 has 64 divisors (see below), whose sum is σ = 446247936. Its totient is φ = 36718272.

The previous prime is 161668267. The next prime is 161668291. The reversal of 161668290 is 92866161.

It is a super-2 number, since 2×161668290² = 52273271983048200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (161668291) 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 31 ways as a sum of consecutive naturals, for example, 31869 + ... + 36591.

It is an arithmetic number, because the mean of its divisors is an integer number (6972624).

Almost surely, 2^161668290 is an apocalyptic number.

161668290 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 161668290, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (223123968).

161668290 is an abundant number, since it is smaller than the sum of its proper divisors (284579646).

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

161668290 is a wasteful number, since it uses less digits than its factorization.

161668290 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4903.

The product of its (nonzero) digits is 31104, while the sum is 39.

The square root of 161668290 is about 12714.8845846118. The cubic root of 161668290 is about 544.7638513430.

The spelling of 161668290 in words is "one hundred sixty-one million, six hundred sixty-eight thousand, two hundred ninety".