81787614437520 has 240 divisors, whose sum is σ = 275656714809840. Its totient is φ = 21731804430336.

The previous prime is 81787614437509. The next prime is 81787614437651. The reversal of 81787614437520 is 2573441678718.

It is a happy number.

81787614437520 is a `hidden beast` number, since 8 + 1 + 7 + 8 + 7 + 61 + 4 + 43 + 7 + 520 = 666.

It can be written as a sum of positive squares in 8 ways, for example, as 3674612957184 + 78113001480336 = 1916928^2 + 8838156^2 .

It is a tau number, because it is divible by the number of its divisors (240).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 267679396 + ... + 267984764.

It is an arithmetic number, because the mean of its divisors is an integer number (1148569645041).

Almost surely, 2^{81787614437520} is an apocalyptic number.

81787614437520 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 81787614437520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (137828357404920).

81787614437520 is an abundant number, since it is smaller than the sum of its proper divisors (193869100372320).

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

81787614437520 is a wasteful number, since it uses less digits than its factorization.

81787614437520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 306722 (or 306713 counting only the distinct ones).

The product of its (nonzero) digits is 63221760, while the sum is 63.

The spelling of 81787614437520 in words is "eighty-one trillion, seven hundred eighty-seven billion, six hundred fourteen million, four hundred thirty-seven thousand, five hundred twenty".