81651722208 has 96 divisors (see below), whose sum is σ = 246006948096. Its totient is φ = 23228894208.

The previous prime is 81651722161. The next prime is 81651722227. The reversal of 81651722208 is 80222715618.

It is a tau number, because it is divible by the number of its divisors (96).

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a self number, because there is not a number n which added to its sum of digits gives 81651722208.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 104166 + ... + 417317.

It is an arithmetic number, because the mean of its divisors is an integer number (2562572376).

Almost surely, 2^81651722208 is an apocalyptic number.

It is an amenable number.

81651722208 is an abundant number, since it is smaller than the sum of its proper divisors (164355225888).

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

81651722208 is a wasteful number, since it uses less digits than its factorization.

81651722208 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 521736 (or 521728 counting only the distinct ones).

The product of its (nonzero) digits is 107520, while the sum is 42.

The spelling of 81651722208 in words is "eighty-one billion, six hundred fifty-one million, seven hundred twenty-two thousand, two hundred eight".