18010781 has 2 divisors, whose sum is σ = 18010782. Its totient is φ = 18010780.

The previous prime is 18010757. The next prime is 18010787. The reversal of 18010781 is 18701081.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13388281 + 4622500 = 3659^2 + 2150^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18010781 is a prime.

It is a super-2 number, since 2×18010781² = 648776464459922, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 18010781.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18010787) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9005390 + 9005391.

It is an arithmetic number, because the mean of its divisors is an integer number (9005391).

Almost surely, 2^18010781 is an apocalyptic number.

It is an amenable number.

18010781 is a deficient number, since it is larger than the sum of its proper divisors (1).

18010781 is an equidigital number, since it uses as much as digits as its factorization.

18010781 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 448, while the sum is 26.

The square root of 18010781 is about 4243.9110499632. The cubic root of 18010781 is about 262.1264515949.

The spelling of 18010781 in words is "eighteen million, ten thousand, seven hundred eighty-one".