81306872064 has 720 divisors, whose sum is σ = 283314588480. Its totient is φ = 22932357120.

The previous prime is 81306872051. The next prime is 81306872071. The reversal of 81306872064 is 46027860318.

It is a super-2 number, since 2×81306872064² (a number of 23 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 316369024 + ... + 316369280.

It is an arithmetic number, because the mean of its divisors is an integer number (393492484).

Almost surely, 2^81306872064 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81306872064, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (141657294240).

81306872064 is an abundant number, since it is smaller than the sum of its proper divisors (202007716416).

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

81306872064 is a wasteful number, since it uses less digits than its factorization.

81306872064 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 388 (or 365 counting only the distinct ones).

The product of its (nonzero) digits is 387072, while the sum is 45.

The spelling of 81306872064 in words is "eighty-one billion, three hundred six million, eight hundred seventy-two thousand, sixty-four".