81431207280 has 320 divisors, whose sum is σ = 289368443520. Its totient is φ = 21032607744.

The previous prime is 81431207261. The next prime is 81431207293. The reversal of 81431207280 is 8270213418.

81431207280 is a `hidden beast` number, since 81 + 431 + 2 + 0 + 72 + 80 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

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, 18619174 + ... + 18623546.

It is an arithmetic number, because the mean of its divisors is an integer number (904276386).

Almost surely, 2^81431207280 is an apocalyptic number.

81431207280 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 81431207280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (144684221760).

81431207280 is an abundant number, since it is smaller than the sum of its proper divisors (207937236240).

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

81431207280 is a wasteful number, since it uses less digits than its factorization.

81431207280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4665 (or 4653 counting only the distinct ones).

The product of its (nonzero) digits is 21504, while the sum is 36.

The spelling of 81431207280 in words is "eighty-one billion, four hundred thirty-one million, two hundred seven thousand, two hundred eighty".