81818537 has 2 divisors, whose sum is σ = 81818538. Its totient is φ = 81818536.

The previous prime is 81818497. The next prime is 81818557. The reversal of 81818537 is 73581818.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 48594841 + 33223696 = 6971^2 + 5764^2 .

It is a cyclic number.

It is not a de Polignac number, because 81818537 - 2⁸ = 81818281 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81818494 and 81818503.

It is not a weakly prime, because it can be changed into another prime (81818557) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40909268 + 40909269.

It is an arithmetic number, because the mean of its divisors is an integer number (40909269).

Almost surely, 2^81818537 is an apocalyptic number.

It is an amenable number.

81818537 is a deficient number, since it is larger than the sum of its proper divisors (1).

81818537 is an equidigital number, since it uses as much as digits as its factorization.

81818537 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 53760, while the sum is 41.

The square root of 81818537 is about 9045.3599707253. The cubic root of 81818537 is about 434.1274392683.

The spelling of 81818537 in words is "eighty-one million, eight hundred eighteen thousand, five hundred thirty-seven".