81859680 has 192 divisors, whose sum is σ = 327559680. Its totient is φ = 18703872.

The previous prime is 81859669. The next prime is 81859681. The reversal of 81859680 is 8695818.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81859681) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 28887 + ... + 31593.

It is an arithmetic number, because the mean of its divisors is an integer number (1706040).

Almost surely, 2^81859680 is an apocalyptic number.

81859680 is a gapful number since it is divisible by the number (80) 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 81859680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (163779840).

81859680 is an abundant number, since it is smaller than the sum of its proper divisors (245700000).

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

81859680 is a wasteful number, since it uses less digits than its factorization.

81859680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2738 (or 2724 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 45.

The square root of 81859680 is about 9047.6339448499. The cubic root of 81859680 is about 434.2001950391.

The spelling of 81859680 in words is "eighty-one million, eight hundred fifty-nine thousand, six hundred eighty".