81964628928 has 672 divisors, whose sum is σ = 303007158272. Its totient is φ = 20603289600.

The previous prime is 81964628899. The next prime is 81964628929. The reversal of 81964628928 is 82982646918.

81964628928 is a `hidden beast` number, since 8 + 1 + 96 + 462 + 89 + 2 + 8 = 666.

It is a tau number, because it is divible by the number of its divisors (672).

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

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81964628929) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 118617063 + ... + 118617753.

Almost surely, 2^81964628928 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81964628928, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (151503579136).

81964628928 is an abundant number, since it is smaller than the sum of its proper divisors (221042529344).

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

81964628928 is a wasteful number, since it uses less digits than its factorization.

81964628928 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 833 (or 820 counting only the distinct ones).

The product of its digits is 23887872, while the sum is 63.

The spelling of 81964628928 in words is "eighty-one billion, nine hundred sixty-four million, six hundred twenty-eight thousand, nine hundred twenty-eight".