81306205836 has 24 divisors (see below), whose sum is σ = 190850499840. Its totient is φ = 26939780112.

The previous prime is 81306205807. The next prime is 81306205837. The reversal of 81306205836 is 63850260318.

It is a super-2 number, since 2×81306205836² (a number of 23 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81306205837) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20283976 + ... + 20287983.

It is an arithmetic number, because the mean of its divisors is an integer number (7952104160).

Almost surely, 2^81306205836 is an apocalyptic number.

It is an amenable number.

81306205836 is an abundant number, since it is smaller than the sum of its proper divisors (109544294004).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81306205836 is a wasteful number, since it uses less digits than its factorization.

81306205836 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40572133 (or 40572131 counting only the distinct ones).

The product of its (nonzero) digits is 207360, while the sum is 42.

The spelling of 81306205836 in words is "eighty-one billion, three hundred six million, two hundred five thousand, eight hundred thirty-six".