81334440 has 384 divisors, whose sum is σ = 323481600. Its totient is φ = 17487360.

The previous prime is 81334397. The next prime is 81334453. The reversal of 81334440 is 4443318.

It is a super-2 number, since 2×81334440² = 13230582260227200, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1730497 + ... + 1730543.

It is an arithmetic number, because the mean of its divisors is an integer number (842400).

Almost surely, 2^81334440 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 81334440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (161740800).

81334440 is an abundant number, since it is smaller than the sum of its proper divisors (242147160).

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

81334440 is a wasteful number, since it uses less digits than its factorization.

81334440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 117 (or 110 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 27.

The square root of 81334440 is about 9018.5608608026. The cubic root of 81334440 is about 433.2695422205.

Adding to 81334440 its reverse (4443318), we get a palindrome (85777758).

It can be divided in two parts, 813 and 34440, that added together give a palindrome (35253).

The spelling of 81334440 in words is "eighty-one million, three hundred thirty-four thousand, four hundred forty".