71216581 has 2 divisors, whose sum is σ = 71216582. Its totient is φ = 71216580.

The previous prime is 71216539. The next prime is 71216597. The reversal of 71216581 is 18561217.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 43020481 + 28196100 = 6559^2 + 5310^2 .

It is a cyclic number.

It is not a de Polignac number, because 71216581 - 2¹⁵ = 71183813 is a prime.

It is a super-2 number, since 2×71216581² = 10143602818659122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (71216681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 35608290 + 35608291.

It is an arithmetic number, because the mean of its divisors is an integer number (35608291).

Almost surely, 2^71216581 is an apocalyptic number.

It is an amenable number.

71216581 is a deficient number, since it is larger than the sum of its proper divisors (1).

71216581 is an equidigital number, since it uses as much as digits as its factorization.

71216581 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 71216581 is about 8438.9917051743. The cubic root of 71216581 is about 414.5023909476.

Adding to 71216581 its reverse (18561217), we get a palindrome (89777798).

The spelling of 71216581 in words is "seventy-one million, two hundred sixteen thousand, five hundred eighty-one".