81271537 has 2 divisors, whose sum is σ = 81271538. Its totient is φ = 81271536.

The previous prime is 81271501. The next prime is 81271559. The reversal of 81271537 is 73517218.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 58384881 + 22886656 = 7641^2 + 4784^2 .

It is a cyclic number.

It is not a de Polignac number, because 81271537 - 2⁷ = 81271409 is a prime.

It is not a weakly prime, because it can be changed into another prime (81278537) 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, 40635768 + 40635769.

It is an arithmetic number, because the mean of its divisors is an integer number (40635769).

Almost surely, 2^81271537 is an apocalyptic number.

It is an amenable number.

81271537 is a deficient number, since it is larger than the sum of its proper divisors (1).

81271537 is an equidigital number, since it uses as much as digits as its factorization.

81271537 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 11760, while the sum is 34.

The square root of 81271537 is about 9015.0727673159. The cubic root of 81271537 is about 433.1578184006.

The spelling of 81271537 in words is "eighty-one million, two hundred seventy-one thousand, five hundred thirty-seven".