81085579 has 2 divisors, whose sum is σ = 81085580. Its totient is φ = 81085578.

The previous prime is 81085549. The next prime is 81085583. The reversal of 81085579 is 97558018.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81085579 - 2⁵ = 81085547 is a prime.

It is a super-2 number, since 2×81085579² = 13149742243530482, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (81085549) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40542789 + 40542790.

It is an arithmetic number, because the mean of its divisors is an integer number (40542790).

Almost surely, 2^81085579 is an apocalyptic number.

81085579 is a deficient number, since it is larger than the sum of its proper divisors (1).

81085579 is an equidigital number, since it uses as much as digits as its factorization.

81085579 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 100800, while the sum is 43.

The square root of 81085579 is about 9004.7531337622. The cubic root of 81085579 is about 432.8271955781.

The spelling of 81085579 in words is "eighty-one million, eighty-five thousand, five hundred seventy-nine".