81530413 has 2 divisors, whose sum is σ = 81530414. Its totient is φ = 81530412.

The previous prime is 81530381. The next prime is 81530417. The reversal of 81530413 is 31403518.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 64208169 + 17322244 = 8013^2 + 4162^2 .

It is a cyclic number.

It is not a de Polignac number, because 81530413 - 2⁵ = 81530381 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81530417) 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, 40765206 + 40765207.

It is an arithmetic number, because the mean of its divisors is an integer number (40765207).

Almost surely, 2^81530413 is an apocalyptic number.

It is an amenable number.

81530413 is a deficient number, since it is larger than the sum of its proper divisors (1).

81530413 is an equidigital number, since it uses as much as digits as its factorization.

81530413 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 81530413 is about 9029.4193058026. The cubic root of 81530413 is about 433.6172466197.

The spelling of 81530413 in words is "eighty-one million, five hundred thirty thousand, four hundred thirteen".