81366757 has 2 divisors, whose sum is σ = 81366758. Its totient is φ = 81366756.

The previous prime is 81366731. The next prime is 81366767. The reversal of 81366757 is 75766318.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 80892036 + 474721 = 8994^2 + 689^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81366757 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81366767) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40683378 + 40683379.

It is an arithmetic number, because the mean of its divisors is an integer number (40683379).

Almost surely, 2^81366757 is an apocalyptic number.

It is an amenable number.

81366757 is a deficient number, since it is larger than the sum of its proper divisors (1).

81366757 is an equidigital number, since it uses as much as digits as its factorization.

81366757 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 211680, while the sum is 43.

The square root of 81366757 is about 9020.3523767090. The cubic root of 81366757 is about 433.3269189715.

The spelling of 81366757 in words is "eighty-one million, three hundred sixty-six thousand, seven hundred fifty-seven".