81566000 has 80 divisors (see below), whose sum is σ = 208915200. Its totient is φ = 30694400.

The previous prime is 81565997. The next prime is 81566011. The reversal of 81566000 is 66518.

It is a tau number, because it is divible by the number of its divisors (80).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 32801 + ... + 35199.

It is an arithmetic number, because the mean of its divisors is an integer number (2611440).

Almost surely, 2^81566000 is an apocalyptic number.

81566000 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 81566000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (104457600).

81566000 is an abundant number, since it is smaller than the sum of its proper divisors (127349200).

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

81566000 is a wasteful number, since it uses less digits than its factorization.

81566000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2439 (or 2423 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 26.

The square root of 81566000 is about 9031.3897048018. The cubic root of 81566000 is about 433.6803269344.

The spelling of 81566000 in words is "eighty-one million, five hundred sixty-six thousand".