8101781 has 2 divisors, whose sum is σ = 8101782. Its totient is φ = 8101780.

The previous prime is 8101777. The next prime is 8101783. The reversal of 8101781 is 1871018.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 8031556 + 70225 = 2834^2 + 265^2 .

It is a cyclic number.

It is not a de Polignac number, because 8101781 - 2² = 8101777 is a prime.

It is a super-2 number, since 2×8101781² = 131277710743922, which contains 22 as substring.

Together with 8101783, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 8101781.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8101783) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4050890 + 4050891.

It is an arithmetic number, because the mean of its divisors is an integer number (4050891).

Almost surely, 2^8101781 is an apocalyptic number.

It is an amenable number.

8101781 is a deficient number, since it is larger than the sum of its proper divisors (1).

8101781 is an equidigital number, since it uses as much as digits as its factorization.

8101781 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 448, while the sum is 26.

The square root of 8101781 is about 2846.3627667604. The cubic root of 8101781 is about 200.8446032063.

Adding to 8101781 its reverse (1871018), we get a palindrome (9972799).

The spelling of 8101781 in words is "eight million, one hundred one thousand, seven hundred eighty-one".