81579529 has 2 divisors, whose sum is σ = 81579530. Its totient is φ = 81579528.

The previous prime is 81579503. The next prime is 81579539. The reversal of 81579529 is 92597518.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 60419529 + 21160000 = 7773^2 + 4600^2 .

It is a cyclic number.

It is not a de Polignac number, because 81579529 - 2¹⁵ = 81546761 is a prime.

It is not a weakly prime, because it can be changed into another prime (81579539) 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, 40789764 + 40789765.

It is an arithmetic number, because the mean of its divisors is an integer number (40789765).

Almost surely, 2^81579529 is an apocalyptic number.

It is an amenable number.

81579529 is a deficient number, since it is larger than the sum of its proper divisors (1).

81579529 is an equidigital number, since it uses as much as digits as its factorization.

81579529 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 226800, while the sum is 46.

The square root of 81579529 is about 9032.1386725404. The cubic root of 81579529 is about 433.7043031695.

The spelling of 81579529 in words is "eighty-one million, five hundred seventy-nine thousand, five hundred twenty-nine".