381736781 has 2 divisors, whose sum is σ = 381736782. Its totient is φ = 381736780.

The previous prime is 381736777. The next prime is 381736787. The reversal of 381736781 is 187637183.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 278389225 + 103347556 = 16685^2 + 10166^2 .

It is an emirp because it is prime and its reverse (187637183) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 381736781 - 2² = 381736777 is a prime.

It is a super-2 number, since 2×381736781² = 291445939936483922, which contains 22 as substring.

It is a Sophie Germain 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 (381736787) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 190868390 + 190868391.

It is an arithmetic number, because the mean of its divisors is an integer number (190868391).

Almost surely, 2^381736781 is an apocalyptic number.

It is an amenable number.

381736781 is a deficient number, since it is larger than the sum of its proper divisors (1).

381736781 is an equidigital number, since it uses as much as digits as its factorization.

381736781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 169344, while the sum is 44.

The square root of 381736781 is about 19538.0853974999. The cubic root of 381736781 is about 725.4174566088.

The spelling of 381736781 in words is "three hundred eighty-one million, seven hundred thirty-six thousand, seven hundred eighty-one".