81305801 has 4 divisors (see below), whose sum is σ = 81899412. Its totient is φ = 80712192.

The previous prime is 81305797. The next prime is 81305827. The reversal of 81305801 is 10850318.

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 66406201 + 14899600 = 8149^2 + 3860^2 .

It is a cyclic number.

It is not a de Polignac number, because 81305801 - 2² = 81305797 is a prime.

It is a super-2 number, since 2×81305801² = 13221266552503202, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81305881) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 296600 + ... + 296873.

It is an arithmetic number, because the mean of its divisors is an integer number (20474853).

Almost surely, 2^81305801 is an apocalyptic number.

It is an amenable number.

81305801 is a deficient number, since it is larger than the sum of its proper divisors (593611).

81305801 is a wasteful number, since it uses less digits than its factorization.

81305801 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 593610.

The product of its (nonzero) digits is 960, while the sum is 26.

The square root of 81305801 is about 9016.9729399616. The cubic root of 81305801 is about 433.2186828179.

It can be divided in two parts, 8130 and 5801, that added together give a palindrome (13931).

The spelling of 81305801 in words is "eighty-one million, three hundred five thousand, eight hundred one".