81778787592 has 16 divisors (see below), whose sum is σ = 204446969040. Its totient is φ = 27259595856.

The previous prime is 81778787581. The next prime is 81778787599. The reversal of 81778787592 is 29578787718.

It is not an unprimeable number, because it can be changed into a prime (81778787599) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1703724718 + ... + 1703724765.

It is an arithmetic number, because the mean of its divisors is an integer number (12777935565).

Almost surely, 2^81778787592 is an apocalyptic number.

It is an amenable number.

81778787592 is an abundant number, since it is smaller than the sum of its proper divisors (122668181448).

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

81778787592 is a wasteful number, since it uses less digits than its factorization.

81778787592 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3407449492 (or 3407449488 counting only the distinct ones).

The product of its digits is 110638080, while the sum is 69.

The spelling of 81778787592 in words is "eighty-one billion, seven hundred seventy-eight million, seven hundred eighty-seven thousand, five hundred ninety-two".