81070081 has 4 divisors (see below), whose sum is σ = 81518164. Its totient is φ = 80622000.

The previous prime is 81070063. The next prime is 81070097. The reversal of 81070081 is 18007018.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 4769856 + 76300225 = 2184^2 + 8735^2 .

It is a cyclic number.

It is not a de Polignac number, because 81070081 - 2¹³ = 81061889 is a prime.

It is a super-2 number, since 2×81070081² = 13144716066693122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81070181) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 223770 + ... + 224131.

It is an arithmetic number, because the mean of its divisors is an integer number (20379541).

Almost surely, 2^81070081 is an apocalyptic number.

It is an amenable number.

81070081 is a deficient number, since it is larger than the sum of its proper divisors (448083).

81070081 is a wasteful number, since it uses less digits than its factorization.

81070081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 448082.

The product of its (nonzero) digits is 448, while the sum is 25.

The square root of 81070081 is about 9003.8925471154. The cubic root of 81070081 is about 432.7996181989.

Adding to 81070081 its reverse (18007018), we get a palindrome (99077099).

The spelling of 81070081 in words is "eighty-one million, seventy thousand, eighty-one".