81784039402640 has 80 divisors (see below), whose sum is σ = 196386837818880. Its totient is φ = 31641379246080.

The previous prime is 81784039402633. The next prime is 81784039402661. The reversal of 81784039402640 is 4620493048718.

It is a happy number.

81784039402640 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (80).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4201505 + ... + 13461824.

It is an arithmetic number, because the mean of its divisors is an integer number (2454835472736).

Almost surely, 2^{81784039402640} is an apocalyptic number.

81784039402640 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81784039402640 is an abundant number, since it is smaller than the sum of its proper divisors (114602798416240).

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

81784039402640 is a wasteful number, since it uses less digits than its factorization.

81784039402640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17665240 (or 17665234 counting only the distinct ones).

The product of its (nonzero) digits is 9289728, while the sum is 56.

The spelling of 81784039402640 in words is "eighty-one trillion, seven hundred eighty-four billion, thirty-nine million, four hundred two thousand, six hundred forty".