81560340 has 72 divisors (see below), whose sum is σ = 249729480. Its totient is φ = 21544704.

The previous prime is 81560309. The next prime is 81560341. The reversal of 81560340 is 4306518.

81560340 is a `hidden beast` number, since 8 + 15 + 603 + 40 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 12404484 + 69155856 = 3522^2 + 8316^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81560341) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 17542 + ... + 21698.

It is an arithmetic number, because the mean of its divisors is an integer number (3468465).

Almost surely, 2^81560340 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 81560340, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (124864740).

81560340 is an abundant number, since it is smaller than the sum of its proper divisors (168169140).

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

81560340 is a wasteful number, since it uses less digits than its factorization.

81560340 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4281 (or 4276 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 27.

The square root of 81560340 is about 9031.0763478115. The cubic root of 81560340 is about 433.6702954367.

Adding to 81560340 its reverse (4306518), we get a palindrome (85866858).

The spelling of 81560340 in words is "eighty-one million, five hundred sixty thousand, three hundred forty".