81268131840 has 768 divisors, whose sum is σ = 312785141760. Its totient is φ = 17623941120.

The previous prime is 81268131839. The next prime is 81268131907. The reversal of 81268131840 is 4813186218.

It is a tau number, because it is divible by the number of its divisors (768).

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a junction number, because it is equal to n+sod(n) for n = 81268131792 and 81268131801.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 486635437 + ... + 486635603.

It is an arithmetic number, because the mean of its divisors is an integer number (407272320).

Almost surely, 2^81268131840 is an apocalyptic number.

81268131840 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 81268131840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (156392570880).

81268131840 is an abundant number, since it is smaller than the sum of its proper divisors (231517009920).

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

81268131840 is a wasteful number, since it uses less digits than its factorization.

81268131840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 308 (or 288 counting only the distinct ones).

The product of its (nonzero) digits is 73728, while the sum is 42.

The spelling of 81268131840 in words is "eighty-one billion, two hundred sixty-eight million, one hundred thirty-one thousand, eight hundred forty".