161689120 has 48 divisors (see below), whose sum is σ = 383405400. Its totient is φ = 64436224.

The previous prime is 161689097. The next prime is 161689127. The reversal of 161689120 is 21986161.

It can be written as a sum of positive squares in 4 ways, for example, as 118287376 + 43401744 = 10876^2 + 6588^2 .

It is a super-2 number, since 2×161689120² = 52286743052748800, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (161689127) by changing a digit.

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, 45156 + ... + 48604.

Almost surely, 2^161689120 is an apocalyptic number.

161689120 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 161689120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (191702700).

161689120 is an abundant number, since it is smaller than the sum of its proper divisors (221716280).

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

161689120 is a wasteful number, since it uses less digits than its factorization.

161689120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3757 (or 3749 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 34.

The square root of 161689120 is about 12715.7036769500. The cubic root of 161689120 is about 544.7872468683.

The spelling of 161689120 in words is "one hundred sixty-one million, six hundred eighty-nine thousand, one hundred twenty".