18736681 has 2 divisors, whose sum is σ = 18736682. Its totient is φ = 18736680.

The previous prime is 18736637. The next prime is 18736693. The reversal of 18736681 is 18663781.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12531600 + 6205081 = 3540^2 + 2491^2 .

It is an emirp because it is prime and its reverse (18663781) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18736681 - 2⁹ = 18736169 is a prime.

It is a super-2 number, since 2×18736681² = 702126429791522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (18736481) 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, 9368340 + 9368341.

It is an arithmetic number, because the mean of its divisors is an integer number (9368341).

Almost surely, 2^18736681 is an apocalyptic number.

It is an amenable number.

18736681 is a deficient number, since it is larger than the sum of its proper divisors (1).

18736681 is an equidigital number, since it uses as much as digits as its factorization.

18736681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 48384, while the sum is 40.

The square root of 18736681 is about 4328.5888000594. The cubic root of 18736681 is about 265.6017227307.

Subtracting from 18736681 its reverse (18663781), we obtain a square (72900 = 270²).

The spelling of 18736681 in words is "eighteen million, seven hundred thirty-six thousand, six hundred eighty-one".