81284579 has 2 divisors, whose sum is σ = 81284580. Its totient is φ = 81284578.

The previous prime is 81284549. The next prime is 81284627. The reversal of 81284579 is 97548218.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81284579 - 2¹² = 81280483 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (81284519) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40642289 + 40642290.

It is an arithmetic number, because the mean of its divisors is an integer number (40642290).

Almost surely, 2^81284579 is an apocalyptic number.

81284579 is a deficient number, since it is larger than the sum of its proper divisors (1).

81284579 is an equidigital number, since it uses as much as digits as its factorization.

81284579 is an evil number, because the sum of its binary digits is even.

The product of its digits is 161280, while the sum is 44.

The square root of 81284579 is about 9015.7960824322. The cubic root of 81284579 is about 433.1809874063.

The spelling of 81284579 in words is "eighty-one million, two hundred eighty-four thousand, five hundred seventy-nine".