161909540 has 24 divisors (see below), whose sum is σ = 366165240. Its totient is φ = 59781888.

The previous prime is 161909483. The next prime is 161909551. The reversal of 161909540 is 45909161.

It can be written as a sum of positive squares in 4 ways, for example, as 1532644 + 160376896 = 1238^2 + 12664^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 161909540.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 311105 + ... + 311624.

It is an arithmetic number, because the mean of its divisors is an integer number (15256885).

Almost surely, 2^161909540 is an apocalyptic number.

161909540 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

161909540 is an abundant number, since it is smaller than the sum of its proper divisors (204255700).

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

161909540 is a wasteful number, since it uses less digits than its factorization.

161909540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 622751 (or 622749 counting only the distinct ones).

The product of its (nonzero) digits is 9720, while the sum is 35.

The square root of 161909540 is about 12724.3679607280. The cubic root of 161909540 is about 545.0346918410.

The spelling of 161909540 in words is "one hundred sixty-one million, nine hundred nine thousand, five hundred forty".