81003761 has 2 divisors, whose sum is σ = 81003762. Its totient is φ = 81003760.

The previous prime is 81003751. The next prime is 81003763. The reversal of 81003761 is 16730018.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 78872161 + 2131600 = 8881^2 + 1460^2 .

It is a cyclic number.

It is not a de Polignac number, because 81003761 - 2⁶ = 81003697 is a prime.

It is a super-2 number, since 2×81003761² = 13123218592290242, which contains 22 as substring.

Together with 81003763, 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 81003761.

It is not a weakly prime, because it can be changed into another prime (81003763) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40501880 + 40501881.

It is an arithmetic number, because the mean of its divisors is an integer number (40501881).

Almost surely, 2^81003761 is an apocalyptic number.

It is an amenable number.

81003761 is a deficient number, since it is larger than the sum of its proper divisors (1).

81003761 is an equidigital number, since it uses as much as digits as its factorization.

81003761 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1008, while the sum is 26.

The square root of 81003761 is about 9000.2089420191. The cubic root of 81003761 is about 432.6815676560.

Adding to 81003761 its reverse (16730018), we get a palindrome (97733779).

The spelling of 81003761 in words is "eighty-one million, three thousand, seven hundred sixty-one".