81722657700 has 180 divisors, whose sum is σ = 269257027732. Its totient is φ = 21435321600.

The previous prime is 81722657657. The next prime is 81722657711. The reversal of 81722657700 is 775622718.

81722657700 is a `hidden beast` number, since 8 + 1 + 72 + 2 + 6 + 577 + 0 + 0 = 666.

It can be written as a sum of positive squares in 6 ways, for example, as 43199959716 + 38522697984 = 207846^2 + 196272^2 .

It is a tau number, because it is divible by the number of its divisors (180).

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

It is an unprimeable number.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 411402 + ... + 576798.

Almost surely, 2^81722657700 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 81722657700, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (134628513866).

81722657700 is an abundant number, since it is smaller than the sum of its proper divisors (187534370032).

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

81722657700 is a wasteful number, since it uses less digits than its factorization.

81722657700 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 165484 (or 165468 counting only the distinct ones).

The product of its (nonzero) digits is 329280, while the sum is 45.

The spelling of 81722657700 in words is "eighty-one billion, seven hundred twenty-two million, six hundred fifty-seven thousand, seven hundred".