18025781 has 2 divisors, whose sum is σ = 18025782. Its totient is φ = 18025780.

The previous prime is 18025753. The next prime is 18025783. The reversal of 18025781 is 18752081.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12460900 + 5564881 = 3530^2 + 2359^2 .

It is a cyclic number.

It is not a de Polignac number, because 18025781 - 2⁶ = 18025717 is a prime.

It is a super-2 number, since 2×18025781² = 649857561319922, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 18025783, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18025783) 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, 9012890 + 9012891.

It is an arithmetic number, because the mean of its divisors is an integer number (9012891).

Almost surely, 2^18025781 is an apocalyptic number.

It is an amenable number.

18025781 is a deficient number, since it is larger than the sum of its proper divisors (1).

18025781 is an equidigital number, since it uses as much as digits as its factorization.

18025781 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4480, while the sum is 32.

The square root of 18025781 is about 4245.6779199558. The cubic root of 18025781 is about 262.1992007210.

The spelling of 18025781 in words is "eighteen million, twenty-five thousand, seven hundred eighty-one".