18016781 has 2 divisors, whose sum is σ = 18016782. Its totient is φ = 18016780.

The previous prime is 18016759. The next prime is 18016783. The reversal of 18016781 is 18761081.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17724100 + 292681 = 4210^2 + 541^2 .

It is a cyclic number.

It is not a de Polignac number, because 18016781 - 2⁶ = 18016717 is a prime.

It is a super-2 number, since 2×18016781² = 649208795203922, which contains 22 as substring.

Together with 18016783, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18016783) 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, 9008390 + 9008391.

It is an arithmetic number, because the mean of its divisors is an integer number (9008391).

Almost surely, 2^18016781 is an apocalyptic number.

It is an amenable number.

18016781 is a deficient number, since it is larger than the sum of its proper divisors (1).

18016781 is an equidigital number, since it uses as much as digits as its factorization.

18016781 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2688, while the sum is 32.

The square root of 18016781 is about 4244.6178862178. The cubic root of 18016781 is about 262.1555560906.

It can be divided in two parts, 180 and 16781, that added together give a palindrome (16961).

The spelling of 18016781 in words is "eighteen million, sixteen thousand, seven hundred eighty-one".