81579539 has 2 divisors, whose sum is σ = 81579540. Its totient is φ = 81579538.

The previous prime is 81579529. The next prime is 81579571. The reversal of 81579539 is 93597518.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81579539 - 2⁸ = 81579283 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 81579493 and 81579502.

It is not a weakly prime, because it can be changed into another prime (81579529) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40789769 + 40789770.

It is an arithmetic number, because the mean of its divisors is an integer number (40789770).

Almost surely, 2^81579539 is an apocalyptic number.

81579539 is a deficient number, since it is larger than the sum of its proper divisors (1).

81579539 is an equidigital number, since it uses as much as digits as its factorization.

81579539 is an evil number, because the sum of its binary digits is even.

The product of its digits is 340200, while the sum is 47.

The square root of 81579539 is about 9032.1392261191. The cubic root of 81579539 is about 433.7043208906.

The spelling of 81579539 in words is "eighty-one million, five hundred seventy-nine thousand, five hundred thirty-nine".