18821161 has 2 divisors, whose sum is σ = 18821162. Its totient is φ = 18821160.

The previous prime is 18821147. The next prime is 18821213. The reversal of 18821161 is 16112881.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16321600 + 2499561 = 4040^2 + 1581^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18821161 is a prime.

It is a super-2 number, since 2×18821161² = 708472202775842, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (18821111) 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 as a sum of consecutive naturals, namely, 9410580 + 9410581.

It is an arithmetic number, because the mean of its divisors is an integer number (9410581).

Almost surely, 2^18821161 is an apocalyptic number.

It is an amenable number.

18821161 is a deficient number, since it is larger than the sum of its proper divisors (1).

18821161 is an equidigital number, since it uses as much as digits as its factorization.

18821161 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 768, while the sum is 28.

The square root of 18821161 is about 4338.3362018175. The cubic root of 18821161 is about 266.0003062163. Note that the first 3 decimals are identical.

The spelling of 18821161 in words is "eighteen million, eight hundred twenty-one thousand, one hundred sixty-one".