81272340 has 144 divisors (see below), whose sum is σ = 261975168. Its totient is φ = 20351232.

The previous prime is 81272339. The next prime is 81272357. The reversal of 81272340 is 4327218.

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 47 ways as a sum of consecutive naturals, for example, 277234 + ... + 277526.

It is an arithmetic number, because the mean of its divisors is an integer number (1819272).

Almost surely, 2^81272340 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 81272340, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (130987584).

81272340 is an abundant number, since it is smaller than the sum of its proper divisors (180702828).

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

81272340 is a wasteful number, since it uses less digits than its factorization.

81272340 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 398 (or 393 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 27.

The square root of 81272340 is about 9015.1173037293. The cubic root of 81272340 is about 433.1592449951.

Adding to 81272340 its reverse (4327218), we get a palindrome (85599558).

The spelling of 81272340 in words is "eighty-one million, two hundred seventy-two thousand, three hundred forty".