161091812 has 18 divisors (see below), whose sum is σ = 327937302. Its totient is φ = 69039264.

The previous prime is 161091811. The next prime is 161091907. The reversal of 161091812 is 218190161.

It can be written as a sum of positive squares in only one way, i.e., 139617856 + 21473956 = 11816^2 + 4634^2 .

It is not an unprimeable number, because it can be changed into a prime (161091811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 410753 + ... + 411144.

It is an arithmetic number, because the mean of its divisors is an integer number (18218739).

Almost surely, 2^161091812 is an apocalyptic number.

It is an amenable number.

161091812 is an abundant number, since it is smaller than the sum of its proper divisors (166845490).

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

161091812 is a wasteful number, since it uses less digits than its factorization.

161091812 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 821915 (or 821906 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 29.

The square root of 161091812 is about 12692.1949244408. The cubic root of 161091812 is about 544.1155725110.

The spelling of 161091812 in words is "one hundred sixty-one million, ninety-one thousand, eight hundred twelve".