81565459 has 2 divisors, whose sum is σ = 81565460. Its totient is φ = 81565458.

The previous prime is 81565403. The next prime is 81565469. The reversal of 81565459 is 95456518.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81565459 is a prime.

It is not a weakly prime, because it can be changed into another prime (81565469) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40782729 + 40782730.

It is an arithmetic number, because the mean of its divisors is an integer number (40782730).

Almost surely, 2^81565459 is an apocalyptic number.

81565459 is a deficient number, since it is larger than the sum of its proper divisors (1).

81565459 is an equidigital number, since it uses as much as digits as its factorization.

81565459 is an evil number, because the sum of its binary digits is even.

The product of its digits is 216000, while the sum is 43.

The square root of 81565459 is about 9031.3597536584. The cubic root of 81565459 is about 433.6793681134.

The spelling of 81565459 in words is "eighty-one million, five hundred sixty-five thousand, four hundred fifty-nine".