81512371 has 2 divisors, whose sum is σ = 81512372. Its totient is φ = 81512370.

The previous prime is 81512363. The next prime is 81512381. The reversal of 81512371 is 17321518.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81512371 - 2³ = 81512363 is a prime.

It is not a weakly prime, because it can be changed into another prime (81512351) 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, 40756185 + 40756186.

It is an arithmetic number, because the mean of its divisors is an integer number (40756186).

Almost surely, 2^81512371 is an apocalyptic number.

81512371 is a deficient number, since it is larger than the sum of its proper divisors (1).

81512371 is an equidigital number, since it uses as much as digits as its factorization.

81512371 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1680, while the sum is 28.

The square root of 81512371 is about 9028.4201829556. The cubic root of 81512371 is about 433.5852589673.

Adding to 81512371 its reverse (17321518), we get a palindrome (98833889).

The spelling of 81512371 in words is "eighty-one million, five hundred twelve thousand, three hundred seventy-one".