81373473680 has 80 divisors (see below), whose sum is σ = 192856250160. Its totient is φ = 31919806464.

The previous prime is 81373473661. The next prime is 81373473683. The reversal of 81373473680 is 8637437318.

It can be written as a sum of positive squares in 8 ways, for example, as 17328036496 + 64045437184 = 131636^2 + 253072^2 .

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

It is not an unprimeable number, because it can be changed into a prime (81373473683) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13179074 + ... + 13185246.

It is an arithmetic number, because the mean of its divisors is an integer number (2410703127).

Almost surely, 2^81373473680 is an apocalyptic number.

81373473680 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81373473680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (96428125080).

81373473680 is an abundant number, since it is smaller than the sum of its proper divisors (111482776480).

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

81373473680 is a wasteful number, since it uses less digits than its factorization.

81373473680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9348 (or 9342 counting only the distinct ones).

The product of its (nonzero) digits is 2032128, while the sum is 50.

The spelling of 81373473680 in words is "eighty-one billion, three hundred seventy-three million, four hundred seventy-three thousand, six hundred eighty".