81711968 has 48 divisors (see below), whose sum is σ = 175271040. Its totient is φ = 37272576.

The previous prime is 81711967. The next prime is 81711977. The reversal of 81711968 is 86911718.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81711961) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 35921 + ... + 38127.

It is an arithmetic number, because the mean of its divisors is an integer number (3651480).

Almost surely, 2^81711968 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 81711968, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (87635520).

81711968 is an abundant number, since it is smaller than the sum of its proper divisors (93559072).

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

81711968 is a wasteful number, since it uses less digits than its factorization.

81711968 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2319 (or 2311 counting only the distinct ones).

The product of its digits is 24192, while the sum is 41.

The square root of 81711968 is about 9039.4672409385. The cubic root of 81711968 is about 433.9388730831.

The spelling of 81711968 in words is "eighty-one million, seven hundred eleven thousand, nine hundred sixty-eight".