81646880 has 96 divisors (see below), whose sum is σ = 222082560. Its totient is φ = 27786240.

The previous prime is 81646841. The next prime is 81646883. The reversal of 81646880 is 8864618.

It is a hoax number, since the sum of its digits (41) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (81646883) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 301145 + ... + 301415.

It is an arithmetic number, because the mean of its divisors is an integer number (2313360).

Almost surely, 2^81646880 is an apocalyptic number.

81646880 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 81646880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (111041280).

81646880 is an abundant number, since it is smaller than the sum of its proper divisors (140435680).

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

81646880 is a wasteful number, since it uses less digits than its factorization.

81646880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 562 (or 554 counting only the distinct ones).

The product of its (nonzero) digits is 73728, while the sum is 41.

The square root of 81646880 is about 9035.8663115387. The cubic root of 81646880 is about 433.8236238863.

The spelling of 81646880 in words is "eighty-one million, six hundred forty-six thousand, eight hundred eighty".