81306140 has 48 divisors (see below), whose sum is σ = 178476480. Its totient is φ = 31073280.

The previous prime is 81306139. The next prime is 81306191. The reversal of 81306140 is 4160318.

It is a super-2 number, since 2×81306140² = 13221376803399200, 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 (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 59060 + ... + 60420.

It is an arithmetic number, because the mean of its divisors is an integer number (3718260).

Almost surely, 2^81306140 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81306140, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (89238240).

81306140 is an abundant number, since it is smaller than the sum of its proper divisors (97170340).

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

81306140 is a wasteful number, since it uses less digits than its factorization.

81306140 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1502 (or 1500 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 23.

The square root of 81306140 is about 9016.9917378248. The cubic root of 81306140 is about 433.2192849108.

Adding to 81306140 its reverse (4160318), we get a palindrome (85466458).

The spelling of 81306140 in words is "eighty-one million, three hundred six thousand, one hundred forty".