81544320000 has 1650 divisors, whose sum is σ = 360191884514. Its totient is φ = 18247680000.

The previous prime is 81544319999. The next prime is 81544320031. The reversal of 81544320000 is 2344518.

81544320000 is a `hidden beast` number, since 8 + 15 + 443 + 200 + 0 + 0 = 666.

It can be written as a sum of positive squares in 5 ways, for example, as 47782462464 + 33761857536 = 218592^2 + 183744^2 .

It is a tau number, because it is divible by the number of its divisors (1650).

It is a super-2 number, since 2×81544320000² (a number of 23 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 149 ways as a sum of consecutive naturals, for example, 6272639994 + ... + 6272640006.

Almost surely, 2^81544320000 is an apocalyptic number.

81544320000 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 81544320000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (180095942257).

81544320000 is an abundant number, since it is smaller than the sum of its proper divisors (278647564514).

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

81544320000 is a wasteful number, since it uses less digits than its factorization.

81544320000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87 (or 34 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 27.

Adding to 81544320000 its reverse (2344518), we get a palindrome (81546664518).

The spelling of 81544320000 in words is "eighty-one billion, five hundred forty-four million, three hundred twenty thousand".