394781385781 has 2 divisors, whose sum is σ = 394781385782. Its totient is φ = 394781385780.

The previous prime is 394781385743. The next prime is 394781385793. The reversal of 394781385781 is 187583187493.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 393913140625 + 868245156 = 627625^2 + 29466^2 .

It is a cyclic number.

It is not a de Polignac number, because 394781385781 - 2²⁹ = 394244514869 is a prime.

It is a super-2 number, since 2×394781385781² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (394781385881) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 197390692890 + 197390692891.

It is an arithmetic number, because the mean of its divisors is an integer number (197390692891).

Almost surely, 2^394781385781 is an apocalyptic number.

It is an amenable number.

394781385781 is a deficient number, since it is larger than the sum of its proper divisors (1).

394781385781 is an equidigital number, since it uses as much as digits as its factorization.

394781385781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 40642560, while the sum is 64.

The spelling of 394781385781 in words is "three hundred ninety-four billion, seven hundred eighty-one million, three hundred eighty-five thousand, seven hundred eighty-one".