81859579 has 2 divisors, whose sum is σ = 81859580. Its totient is φ = 81859578.

The previous prime is 81859549. The next prime is 81859597. The reversal of 81859579 is 97595818.

Together with next prime (81859597) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81859579 - 2⁹ = 81859067 is a prime.

It is not a weakly prime, because it can be changed into another prime (81859529) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40929789 + 40929790.

It is an arithmetic number, because the mean of its divisors is an integer number (40929790).

Almost surely, 2^81859579 is an apocalyptic number.

81859579 is a deficient number, since it is larger than the sum of its proper divisors (1).

81859579 is an equidigital number, since it uses as much as digits as its factorization.

81859579 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 907200, while the sum is 52.

The square root of 81859579 is about 9047.6283632784. The cubic root of 81859579 is about 434.2000164643.

The spelling of 81859579 in words is "eighty-one million, eight hundred fifty-nine thousand, five hundred seventy-nine".