18766381 has 2 divisors, whose sum is σ = 18766382. Its totient is φ = 18766380.

The previous prime is 18766369. The next prime is 18766387. The reversal of 18766381 is 18366781.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10304100 + 8462281 = 3210^2 + 2909^2 .

It is a cyclic number.

It is not a de Polignac number, because 18766381 - 2¹⁵ = 18733613 is a prime.

It is a super-2 number, since 2×18766381² = 704354111674322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18766387) 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, 9383190 + 9383191.

It is an arithmetic number, because the mean of its divisors is an integer number (9383191).

Almost surely, 2^18766381 is an apocalyptic number.

It is an amenable number.

18766381 is a deficient number, since it is larger than the sum of its proper divisors (1).

18766381 is an equidigital number, since it uses as much as digits as its factorization.

18766381 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 18766381 is about 4332.0181209224. The cubic root of 18766381 is about 265.7419860429.

The spelling of 18766381 in words is "eighteen million, seven hundred sixty-six thousand, three hundred eighty-one".