181668397 has 4 divisors (see below), whose sum is σ = 183467196. Its totient is φ = 179869600.

The previous prime is 181668359. The next prime is 181668419. The reversal of 181668397 is 793866181.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 177262596 + 4405801 = 13314^2 + 2099^2 .

It is a cyclic number.

It is not a de Polignac number, because 181668397 - 2²³ = 173279789 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 181668397.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (181668317) 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, 899248 + ... + 899449.

It is an arithmetic number, because the mean of its divisors is an integer number (45866799).

Almost surely, 2^181668397 is an apocalyptic number.

It is an amenable number.

181668397 is a deficient number, since it is larger than the sum of its proper divisors (1798799).

181668397 is a wasteful number, since it uses less digits than its factorization.

181668397 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1798798.

The product of its digits is 435456, while the sum is 49.

The square root of 181668397 is about 13478.4419351793. The cubic root of 181668397 is about 566.3607237018.

The spelling of 181668397 in words is "one hundred eighty-one million, six hundred sixty-eight thousand, three hundred ninety-seven".