81957829472064 has 896 divisors, whose sum is σ = 306741697920000. Its totient is φ = 21319006076928.

The previous prime is 81957829472033. The next prime is 81957829472087. The reversal of 81957829472064 is 46027492875918.

It is a happy number.

81957829472064 is a `hidden beast` number, since 8 + 1 + 9 + 5 + 78 + 29 + 472 + 0 + 64 = 666.

It is a Harshad number since it is a multiple of its sum of digits (72).

It is a junction number, because it is equal to n+sod(n) for n = 81957829471983 and 81957829472001.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 562403242 + ... + 562548950.

It is an arithmetic number, because the mean of its divisors is an integer number (342345645000).

Almost surely, 2^{81957829472064} is an apocalyptic number.

81957829472064 is a gapful number since it is divisible by the number (84) 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 81957829472064, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (153370848960000).

81957829472064 is an abundant number, since it is smaller than the sum of its proper divisors (224783868447936).

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

81957829472064 is a wasteful number, since it uses less digits than its factorization.

81957829472064 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 145837 (or 145807 counting only the distinct ones).

The product of its (nonzero) digits is 487710720, while the sum is 72.

The spelling of 81957829472064 in words is "eighty-one trillion, nine hundred fifty-seven billion, eight hundred twenty-nine million, four hundred seventy-two thousand, sixty-four".