161509640 has 16 divisors (see below), whose sum is σ = 363396780. Its totient is φ = 64603840.

The previous prime is 161509631. The next prime is 161509643. The reversal of 161509640 is 46905161.

It can be written as a sum of positive squares in 2 ways, for example, as 148303684 + 13205956 = 12178^2 + 3634^2 .

It is a junction number, because it is equal to n+sod(n) for n = 161509597 and 161509606.

It is not an unprimeable number, because it can be changed into a prime (161509643) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2018831 + ... + 2018910.

Almost surely, 2^161509640 is an apocalyptic number.

161509640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

161509640 is an abundant number, since it is smaller than the sum of its proper divisors (201887140).

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

161509640 is a wasteful number, since it uses less digits than its factorization.

161509640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4037752 (or 4037748 counting only the distinct ones).

The product of its (nonzero) digits is 6480, while the sum is 32.

The square root of 161509640 is about 12708.6443022063. The cubic root of 161509640 is about 544.5855952535.

The spelling of 161509640 in words is "one hundred sixty-one million, five hundred nine thousand, six hundred forty".