8131681 has 2 divisors, whose sum is σ = 8131682. Its totient is φ = 8131680.

The previous prime is 8131667. The next prime is 8131691. The reversal of 8131681 is 1861318.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 6843456 + 1288225 = 2616^2 + 1135^2 .

It is a cyclic number.

It is not a de Polignac number, because 8131681 - 2⁷ = 8131553 is a prime.

It is a super-2 number, since 2×8131681² = 132248471771522, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8131621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4065840 + 4065841.

It is an arithmetic number, because the mean of its divisors is an integer number (4065841).

Almost surely, 2^8131681 is an apocalyptic number.

It is an amenable number.

8131681 is a deficient number, since it is larger than the sum of its proper divisors (1).

8131681 is an equidigital number, since it uses as much as digits as its factorization.

8131681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1152, while the sum is 28.

The square root of 8131681 is about 2851.6102468605. The cubic root of 8131681 is about 201.0913753333.

Adding to 8131681 its reverse (1861318), we get a palindrome (9992999).

The spelling of 8131681 in words is "eight million, one hundred thirty-one thousand, six hundred eighty-one".