81666080 has 48 divisors (see below), whose sum is σ = 194503680. Its totient is φ = 32401152.

The previous prime is 81666071. The next prime is 81666131. The reversal of 81666080 is 8066618.

It is a self number, because there is not a number n which added to its sum of digits gives 81666080.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18311 + ... + 22329.

It is an arithmetic number, because the mean of its divisors is an integer number (4052160).

Almost surely, 2^81666080 is an apocalyptic number.

81666080 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 81666080, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (97251840).

81666080 is an abundant number, since it is smaller than the sum of its proper divisors (112837600).

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

81666080 is a wasteful number, since it uses less digits than its factorization.

81666080 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4161 (or 4153 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 35.

The square root of 81666080 is about 9036.9286818033. The cubic root of 81666080 is about 433.8576270666.

The spelling of 81666080 in words is "eighty-one million, six hundred sixty-six thousand, eighty".