161405140 has 108 divisors (see below), whose sum is σ = 396090324. Its totient is φ = 55031808.

The previous prime is 161405093. The next prime is 161405143. The reversal of 161405140 is 41504161.

It can be written as a sum of positive squares in 18 ways, for example, as 94361796 + 67043344 = 9714^2 + 8188^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161405143) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 3045354 + ... + 3045406.

It is an arithmetic number, because the mean of its divisors is an integer number (3667503).

Almost surely, 2^161405140 is an apocalyptic number.

161405140 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 161405140, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (198045162).

161405140 is an abundant number, since it is smaller than the sum of its proper divisors (234685184).

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

161405140 is a wasteful number, since it uses less digits than its factorization.

161405140 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 158 (or 90 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 22.

The square root of 161405140 is about 12704.5322621496. The cubic root of 161405140 is about 544.4681172856.

The spelling of 161405140 in words is "one hundred sixty-one million, four hundred five thousand, one hundred forty".