81223857236 has 6 divisors (see below), whose sum is σ = 142141750170. Its totient is φ = 40611928616.

The previous prime is 81223857229. The next prime is 81223857287. The reversal of 81223857236 is 63275832218.

It can be written as a sum of positive squares in only one way, i.e., 41461104400 + 39762752836 = 203620^2 + 199406^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10152982151 + ... + 10152982158.

It is an arithmetic number, because the mean of its divisors is an integer number (23690291695).

Almost surely, 2^81223857236 is an apocalyptic number.

It is an amenable number.

81223857236 is a deficient number, since it is larger than the sum of its proper divisors (60917892934).

81223857236 is a wasteful number, since it uses less digits than its factorization.

81223857236 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20305964313 (or 20305964311 counting only the distinct ones).

The product of its digits is 967680, while the sum is 47.

The spelling of 81223857236 in words is "eighty-one billion, two hundred twenty-three million, eight hundred fifty-seven thousand, two hundred thirty-six".