81816768 has 168 divisors, whose sum is σ = 263499600. Its totient is φ = 24053760.

The previous prime is 81816751. The next prime is 81816809. The reversal of 81816768 is 86761818.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 234258 + ... + 234606.

It is an arithmetic number, because the mean of its divisors is an integer number (1568450).

Almost surely, 2^81816768 is an apocalyptic number.

81816768 is a gapful number since it is divisible by the number (88) 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 81816768, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (131749800).

81816768 is an abundant number, since it is smaller than the sum of its proper divisors (181682832).

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

81816768 is a wasteful number, since it uses less digits than its factorization.

81816768 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 415 (or 402 counting only the distinct ones).

The product of its digits is 129024, while the sum is 45.

The square root of 81816768 is about 9045.2621852548. The cubic root of 81816768 is about 434.1243104868.

The spelling of 81816768 in words is "eighty-one million, eight hundred sixteen thousand, seven hundred sixty-eight".