81301440 has 112 divisors (see below), whose sum is σ = 281635200. Its totient is φ = 19706880.

The previous prime is 81301427. The next prime is 81301501. The reversal of 81301440 is 4410318.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6711 + ... + 14409.

It is an arithmetic number, because the mean of its divisors is an integer number (2514600).

Almost surely, 2^81301440 is an apocalyptic number.

81301440 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81301440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (140817600).

81301440 is an abundant number, since it is smaller than the sum of its proper divisors (200333760).

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

81301440 is a wasteful number, since it uses less digits than its factorization.

81301440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7730 (or 7720 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 21.

The square root of 81301440 is about 9016.7311149884. The cubic root of 81301440 is about 433.2109371613.

Adding to 81301440 its reverse (4410318), we get a palindrome (85711758).

The spelling of 81301440 in words is "eighty-one million, three hundred one thousand, four hundred forty".