18426781 has 2 divisors, whose sum is σ = 18426782. Its totient is φ = 18426780.

The previous prime is 18426767. The next prime is 18426817. The reversal of 18426781 is 18762481.

Together with next prime (18426817) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17355556 + 1071225 = 4166^2 + 1035^2 .

It is a cyclic number.

It is not a de Polignac number, because 18426781 - 2⁹ = 18426269 is a prime.

It is a super-2 number, since 2×18426781² = 679092516043922, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18426781.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18426761) by changing a digit.

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 as a sum of consecutive naturals, namely, 9213390 + 9213391.

It is an arithmetic number, because the mean of its divisors is an integer number (9213391).

Almost surely, 2^18426781 is an apocalyptic number.

It is an amenable number.

18426781 is a deficient number, since it is larger than the sum of its proper divisors (1).

18426781 is an equidigital number, since it uses as much as digits as its factorization.

18426781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 21504, while the sum is 37.

The square root of 18426781 is about 4292.6426592485. The cubic root of 18426781 is about 264.1292459054.

The spelling of 18426781 in words is "eighteen million, four hundred twenty-six thousand, seven hundred eighty-one".