181680906 has 64 divisors (see below), whose sum is σ = 406342656. Its totient is φ = 53692800.

The previous prime is 181680899. The next prime is 181680937. The reversal of 181680906 is 609086181.

It is a Smith number, since the sum of its digits (39) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 641841 + ... + 642123.

It is an arithmetic number, because the mean of its divisors is an integer number (6349104).

Almost surely, 2^181680906 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 181680906, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (203171328).

181680906 is an abundant number, since it is smaller than the sum of its proper divisors (224661750).

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

181680906 is a wasteful number, since it uses less digits than its factorization.

181680906 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 507.

The product of its (nonzero) digits is 20736, while the sum is 39.

The square root of 181680906 is about 13478.9059645062. The cubic root of 181680906 is about 566.3737225572.

The spelling of 181680906 in words is "one hundred eighty-one million, six hundred eighty thousand, nine hundred six".