161909280 has 360 divisors, whose sum is σ = 635849676. Its totient is φ = 38568960.

The previous prime is 161909273. The next prime is 161909281. The reversal of 161909280 is 82909161.

161909280 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 150700176 + 11209104 = 12276^2 + 3348^2 .

It is a tau number, because it is divible by the number of its divisors (360).

It is a super-2 number, since 2×161909280² = 52429229900236800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (161909281) by changing a digit.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 5222865 + ... + 5222895.

Almost surely, 2^161909280 is an apocalyptic number.

161909280 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 161909280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (317924838).

161909280 is an abundant number, since it is smaller than the sum of its proper divisors (473940396).

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

161909280 is a wasteful number, since it uses less digits than its factorization.

161909280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 102 (or 54 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 36.

The square root of 161909280 is about 12724.3577441064. The cubic root of 161909280 is about 545.0344000956.

The spelling of 161909280 in words is "one hundred sixty-one million, nine hundred nine thousand, two hundred eighty".