81342440 has 64 divisors (see below), whose sum is σ = 188211600. Its totient is φ = 31629312.

The previous prime is 81342431. The next prime is 81342451. The reversal of 81342440 is 4424318.

It can be written as a sum of positive squares in 8 ways, for example, as 4218916 + 77123524 = 2054^2 + 8782^2 .

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, 259724 + ... + 260036.

Almost surely, 2^81342440 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 81342440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (94105800).

81342440 is an abundant number, since it is smaller than the sum of its proper divisors (106869160).

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

81342440 is a wasteful number, since it uses less digits than its factorization.

81342440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 486 (or 482 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 26.

The square root of 81342440 is about 9019.0043796419. The cubic root of 81342440 is about 433.2837471203.

Adding to 81342440 its reverse (4424318), we get a palindrome (85766758).

The spelling of 81342440 in words is "eighty-one million, three hundred forty-two thousand, four hundred forty".