81664443234 has 36 divisors (see below), whose sum is σ = 194487363798. Its totient is φ = 24746800320.

The previous prime is 81664443227. The next prime is 81664443253. The reversal of 81664443234 is 43234446618.

It can be written as a sum of positive squares in only one way, i.e., 46592517609 + 35071925625 = 215853^2 + 187275^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 81664443234.

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 18745399 + ... + 18749754.

Almost surely, 2^81664443234 is an apocalyptic number.

81664443234 is an abundant number, since it is smaller than the sum of its proper divisors (112822920564).

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

81664443234 is a wasteful number, since it uses less digits than its factorization.

81664443234 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37495183 (or 37495169 counting only the distinct ones).

The product of its digits is 1327104, while the sum is 45.

The spelling of 81664443234 in words is "eighty-one billion, six hundred sixty-four million, four hundred forty-three thousand, two hundred thirty-four".