81782579 has 2 divisors, whose sum is σ = 81782580. Its totient is φ = 81782578.

The previous prime is 81782567. The next prime is 81782599. The reversal of 81782579 is 97528718.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81782579 - 2²⁴ = 65005363 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81782599) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40891289 + 40891290.

It is an arithmetic number, because the mean of its divisors is an integer number (40891290).

Almost surely, 2^81782579 is an apocalyptic number.

81782579 is a deficient number, since it is larger than the sum of its proper divisors (1).

81782579 is an equidigital number, since it uses as much as digits as its factorization.

81782579 is an evil number, because the sum of its binary digits is even.

The product of its digits is 282240, while the sum is 47.

The square root of 81782579 is about 9043.3721033694. The cubic root of 81782579 is about 434.0638324850.

The spelling of 81782579 in words is "eighty-one million, seven hundred eighty-two thousand, five hundred seventy-nine".