81759640320 has 432 divisors, whose sum is σ = 287786876832. Its totient is φ = 21428305920.

The previous prime is 81759640309. The next prime is 81759640331. The reversal of 81759640320 is 2304695718.

81759640320 is a `hidden beast` number, since 8 + 17 + 596 + 40 + 3 + 2 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (81759640309) and next prime (81759640331).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 235618387 + ... + 235618733.

It is an arithmetic number, because the mean of its divisors is an integer number (666173326).

It is a 1-persistent number, because it is pandigital, but 2⋅81759640320 = 163519280640 is not.

Almost surely, 2^81759640320 is an apocalyptic number.

81759640320 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 81759640320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (143893438416).

81759640320 is an abundant number, since it is smaller than the sum of its proper divisors (206027236512).

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

81759640320 is a wasteful number, since it uses less digits than its factorization.

81759640320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 668 (or 651 counting only the distinct ones).

The product of its (nonzero) digits is 362880, while the sum is 45.

The spelling of 81759640320 in words is "eighty-one billion, seven hundred fifty-nine million, six hundred forty thousand, three hundred twenty".