81576613 has 2 divisors, whose sum is σ = 81576614. Its totient is φ = 81576612.

The previous prime is 81576571. The next prime is 81576637. The reversal of 81576613 is 31667518.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 45792289 + 35784324 = 6767^2 + 5982^2 .

It is a cyclic number.

It is not a de Polignac number, because 81576613 - 2²¹ = 79479461 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81576643) 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, 40788306 + 40788307.

It is an arithmetic number, because the mean of its divisors is an integer number (40788307).

Almost surely, 2^81576613 is an apocalyptic number.

It is an amenable number.

81576613 is a deficient number, since it is larger than the sum of its proper divisors (1).

81576613 is an equidigital number, since it uses as much as digits as its factorization.

81576613 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 30240, while the sum is 37.

The square root of 81576613 is about 9031.9772475356. The cubic root of 81576613 is about 433.6991356279.

The spelling of 81576613 in words is "eighty-one million, five hundred seventy-six thousand, six hundred thirteen".