18394781 has 2 divisors, whose sum is σ = 18394782. Its totient is φ = 18394780.

The previous prime is 18394771. The next prime is 18394837. The reversal of 18394781 is 18749381.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16728100 + 1666681 = 4090^2 + 1291^2 .

It is a cyclic number.

It is not a de Polignac number, because 18394781 - 2¹⁸ = 18132637 is a prime.

It is a super-2 number, since 2×18394781² = 676735936075922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18394711) 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, 9197390 + 9197391.

It is an arithmetic number, because the mean of its divisors is an integer number (9197391).

Almost surely, 2^18394781 is an apocalyptic number.

It is an amenable number.

18394781 is a deficient number, since it is larger than the sum of its proper divisors (1).

18394781 is an equidigital number, since it uses as much as digits as its factorization.

18394781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 48384, while the sum is 41.

The square root of 18394781 is about 4288.9137319373. The cubic root of 18394781 is about 263.9762614483.

The spelling of 18394781 in words is "eighteen million, three hundred ninety-four thousand, seven hundred eighty-one".