81533860 has 24 divisors (see below), whose sum is σ = 171984960. Its totient is φ = 32468064.

The previous prime is 81533849. The next prime is 81533863. The reversal of 81533860 is 6833518.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (81533863) 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 7 ways as a sum of consecutive naturals, for example, 4440 + ... + 13519.

It is an arithmetic number, because the mean of its divisors is an integer number (7166040).

Almost surely, 2^81533860 is an apocalyptic number.

It is an amenable number.

81533860 is an abundant number, since it is smaller than the sum of its proper divisors (90451100).

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

81533860 is a wasteful number, since it uses less digits than its factorization.

81533860 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18195 (or 18193 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 34.

The square root of 81533860 is about 9029.6101798472. The cubic root of 81533860 is about 433.6233574583.

The spelling of 81533860 in words is "eighty-one million, five hundred thirty-three thousand, eight hundred sixty".