81264581 has 2 divisors, whose sum is σ = 81264582. Its totient is φ = 81264580.

The previous prime is 81264571. The next prime is 81264587. The reversal of 81264581 is 18546218.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 69472225 + 11792356 = 8335^2 + 3434^2 .

It is a cyclic number.

It is not a de Polignac number, because 81264581 - 2¹⁸ = 81002437 is a prime.

It is a super-2 number, since 2×81264581² = 13207864250211122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81264587) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40632290 + 40632291.

It is an arithmetic number, because the mean of its divisors is an integer number (40632291).

Almost surely, 2^81264581 is an apocalyptic number.

It is an amenable number.

81264581 is a deficient number, since it is larger than the sum of its proper divisors (1).

81264581 is an equidigital number, since it uses as much as digits as its factorization.

81264581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 15360, while the sum is 35.

The square root of 81264581 is about 9014.6869607325. The cubic root of 81264581 is about 433.1454601103.

The spelling of 81264581 in words is "eighty-one million, two hundred sixty-four thousand, five hundred eighty-one".