161123220 has 72 divisors (see below), whose sum is σ = 490622496. Its totient is φ = 42800832.

The previous prime is 161123203. The next prime is 161123231. The reversal of 161123220 is 22321161.

161123220 is a `hidden beast` number, since 1 + 611 + 2 + 32 + 20 = 666.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 161123193 and 161123202.

It is a congruent number.

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 23 ways as a sum of consecutive naturals, for example, 49359 + ... + 52521.

Almost surely, 2^161123220 is an apocalyptic number.

161123220 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 161123220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (245311248).

161123220 is an abundant number, since it is smaller than the sum of its proper divisors (329499276).

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

161123220 is a wasteful number, since it uses less digits than its factorization.

161123220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3461 (or 3456 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

The square root of 161123220 is about 12693.4321599794. The cubic root of 161123220 is about 544.1509322046.

Adding to 161123220 its reverse (22321161), we get a palindrome (183444381).

The spelling of 161123220 in words is "one hundred sixty-one million, one hundred twenty-three thousand, two hundred twenty".