81298566 has 36 divisors (see below), whose sum is σ = 183118572. Its totient is φ = 27033264.

The previous prime is 81298561. The next prime is 81298597. The reversal of 81298566 is 66589218.

81298566 is a `hidden beast` number, since 81 + 2 + 9 + 8 + 566 = 666.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81298561) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 198570 + ... + 198978.

It is an arithmetic number, because the mean of its divisors is an integer number (5086627).

Almost surely, 2^81298566 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81298566, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (91559286).

81298566 is an abundant number, since it is smaller than the sum of its proper divisors (101820006).

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

81298566 is an frugal number, since it uses more digits than its factorization.

81298566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 835 (or 414 counting only the distinct ones).

The product of its digits is 207360, while the sum is 45.

The square root of 81298566 is about 9016.5717431849. The cubic root of 81298566 is about 433.2058324427.

The spelling of 81298566 in words is "eighty-one million, two hundred ninety-eight thousand, five hundred sixty-six".