81768185856 has 512 divisors, whose sum is σ = 282020697600. Its totient is φ = 23219011584.

The previous prime is 81768185809. The next prime is 81768185861. The reversal of 81768185856 is 65858186718.

It is a tau number, because it is divible by the number of its divisors (512).

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

Its product of digits (25804800) is a multiple of the sum of its prime divisors (175).

It is a junction number, because it is equal to n+sod(n) for n = 81768185793 and 81768185802.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 501645231 + ... + 501645393.

It is an arithmetic number, because the mean of its divisors is an integer number (550821675).

Almost surely, 2^81768185856 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 81768185856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (141010348800).

81768185856 is an abundant number, since it is smaller than the sum of its proper divisors (200252511744).

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

81768185856 is an frugal number, since it uses more digits than its factorization.

81768185856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 221 (or 175 counting only the distinct ones).

The product of its digits is 25804800, while the sum is 63.

The spelling of 81768185856 in words is "eighty-one billion, seven hundred sixty-eight million, one hundred eighty-five thousand, eight hundred fifty-six".