81710899578 has 384 divisors, whose sum is σ = 243395942400. Its totient is φ = 19928643840.

The previous prime is 81710899577. The next prime is 81710899591. The reversal of 81710899578 is 87599801718.

It is a super-4 number, since 4×81710899578⁴ (a number of 45 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is not an unprimeable number, because it can be changed into a prime (81710899573) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 723105250 + ... + 723105362.

It is an arithmetic number, because the mean of its divisors is an integer number (633843600).

Almost surely, 2^81710899578 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81710899578, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (121697971200).

81710899578 is an abundant number, since it is smaller than the sum of its proper divisors (161685042822).

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

81710899578 is a wasteful number, since it uses less digits than its factorization.

81710899578 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 286 (or 155 counting only the distinct ones).

The product of its (nonzero) digits is 10160640, while the sum is 63.

The spelling of 81710899578 in words is "eighty-one billion, seven hundred ten million, eight hundred ninety-nine thousand, five hundred seventy-eight".