81241566 has 64 divisors (see below), whose sum is σ = 199093248. Its totient is φ = 21593088.

The previous prime is 81241553. The next prime is 81241571. The reversal of 81241566 is 66514218.

It is a super-2 number, since 2×81241566² = 13200384092264712, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 34606 + ... + 36878.

It is an arithmetic number, because the mean of its divisors is an integer number (3110832).

Almost surely, 2^81241566 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81241566, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (99546624).

81241566 is an abundant number, since it is smaller than the sum of its proper divisors (117851682).

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

81241566 is a wasteful number, since it uses less digits than its factorization.

81241566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2345.

The product of its digits is 11520, while the sum is 33.

The square root of 81241566 is about 9013.4103423732. The cubic root of 81241566 is about 433.1045657711.

The spelling of 81241566 in words is "eighty-one million, two hundred forty-one thousand, five hundred sixty-six".