81018005 has 16 divisors (see below), whose sum is σ = 103647600. Its totient is φ = 60582912.

The previous prime is 81017969. The next prime is 81018013. The reversal of 81018005 is 50081018.

It can be written as a sum of positive squares in 8 ways, for example, as 17926756 + 63091249 = 4234^2 + 7943^2 .

It is a cyclic number.

It is not a de Polignac number, because 81018005 - 2⁸ = 81017749 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9467 + ... + 15863.

It is an arithmetic number, because the mean of its divisors is an integer number (6477975).

Almost surely, 2^81018005 is an apocalyptic number.

81018005 is a gapful number since it is divisible by the number (85) formed by its first and last digit.

It is an amenable number.

81018005 is a deficient number, since it is larger than the sum of its proper divisors (22629595).

81018005 is a wasteful number, since it uses less digits than its factorization.

81018005 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6568.

The product of its (nonzero) digits is 320, while the sum is 23.

The square root of 81018005 is about 9001.0002221975. Note that the first 3 decimals coincide. The cubic root of 81018005 is about 432.7069276103.

The spelling of 81018005 in words is "eighty-one million, eighteen thousand, five".