81680516240 has 40 divisors (see below), whose sum is σ = 195039834360. Its totient is φ = 31789172736.

The previous prime is 81680516219. The next prime is 81680516257. The reversal of 81680516240 is 4261508618.

It can be written as a sum of positive squares in 4 ways, for example, as 17724129424 + 63956386816 = 133132^2 + 252896^2 .

It is a tau number, because it is divible by the number of its divisors (40).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13794425 + ... + 13800344.

It is an arithmetic number, because the mean of its divisors is an integer number (4875995859).

Almost surely, 2^81680516240 is an apocalyptic number.

81680516240 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81680516240 is an abundant number, since it is smaller than the sum of its proper divisors (113359318120).

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

81680516240 is a wasteful number, since it uses less digits than its factorization.

81680516240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27594819 (or 27594813 counting only the distinct ones).

The product of its (nonzero) digits is 92160, while the sum is 41.

The spelling of 81680516240 in words is "eighty-one billion, six hundred eighty million, five hundred sixteen thousand, two hundred forty".