71681521 has 2 divisors, whose sum is σ = 71681522. Its totient is φ = 71681520.

The previous prime is 71681507. The next prime is 71681549. The reversal of 71681521 is 12518617.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 48497296 + 23184225 = 6964^2 + 4815^2 .

It is a cyclic number.

It is not a de Polignac number, because 71681521 - 2¹¹ = 71679473 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (71681221) 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, 35840760 + 35840761.

It is an arithmetic number, because the mean of its divisors is an integer number (35840761).

Almost surely, 2^71681521 is an apocalyptic number.

It is an amenable number.

71681521 is a deficient number, since it is larger than the sum of its proper divisors (1).

71681521 is an equidigital number, since it uses as much as digits as its factorization.

71681521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3360, while the sum is 31.

The square root of 71681521 is about 8466.4940205495. The cubic root of 71681521 is about 415.4024662908.

The spelling of 71681521 in words is "seventy-one million, six hundred eighty-one thousand, five hundred twenty-one".