81571247 has 2 divisors, whose sum is σ = 81571248. Its totient is φ = 81571246.

The previous prime is 81571183. The next prime is 81571283. The reversal of 81571247 is 74217518.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81571247 - 2⁶ = 81571183 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81571747) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40785623 + 40785624.

It is an arithmetic number, because the mean of its divisors is an integer number (40785624).

Almost surely, 2^81571247 is an apocalyptic number.

81571247 is a deficient number, since it is larger than the sum of its proper divisors (1).

81571247 is an equidigital number, since it uses as much as digits as its factorization.

81571247 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 15680, while the sum is 35.

The square root of 81571247 is about 9031.6801869863. The cubic root of 81571247 is about 433.6896260373.

It can be divided in two parts, 81571 and 247, that added together give a palindrome (81818).

The spelling of 81571247 in words is "eighty-one million, five hundred seventy-one thousand, two hundred forty-seven".