81243923520 has 224 divisors, whose sum is σ = 260448039936. Its totient is φ = 21456230400.

The previous prime is 81243923479. The next prime is 81243923533. The reversal of 81243923520 is 2532934218.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 53065155 + ... + 53066685.

It is an arithmetic number, because the mean of its divisors is an integer number (1162714464).

Almost surely, 2^81243923520 is an apocalyptic number.

81243923520 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 81243923520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (130224019968).

81243923520 is an abundant number, since it is smaller than the sum of its proper divisors (179204116416).

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

81243923520 is a wasteful number, since it uses less digits than its factorization.

81243923520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2049 (or 2039 counting only the distinct ones).

The product of its (nonzero) digits is 103680, while the sum is 39.

The spelling of 81243923520 in words is "eighty-one billion, two hundred forty-three million, nine hundred twenty-three thousand, five hundred twenty".