161906220 has 144 divisors (see below), whose sum is σ = 590903040. Its totient is φ = 35054208.

The previous prime is 161906179. The next prime is 161906243. The reversal of 161906220 is 22609161.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 20559 + ... + 27321.

Almost surely, 2^161906220 is an apocalyptic number.

161906220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 161906220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (295451520).

161906220 is an abundant number, since it is smaller than the sum of its proper divisors (428996820).

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

161906220 is a wasteful number, since it uses less digits than its factorization.

161906220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6804 (or 6799 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 27.

The square root of 161906220 is about 12724.2375017130. The cubic root of 161906220 is about 545.0309664530.

The spelling of 161906220 in words is "one hundred sixty-one million, nine hundred six thousand, two hundred twenty".