81505340 has 24 divisors (see below), whose sum is σ = 195613152. Its totient is φ = 27944640.

The previous prime is 81505313. The next prime is 81505343. The reversal of 81505340 is 4350518.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81505343) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 290951 + ... + 291230.

It is an arithmetic number, because the mean of its divisors is an integer number (8150548).

Almost surely, 2^81505340 is an apocalyptic number.

It is an amenable number.

81505340 is an abundant number, since it is smaller than the sum of its proper divisors (114107812).

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

81505340 is a wasteful number, since it uses less digits than its factorization.

81505340 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 582197 (or 582195 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 26.

The square root of 81505340 is about 9028.0307930357. The cubic root of 81505340 is about 433.5727920433.

Adding to 81505340 its reverse (4350518), we get a palindrome (85855858).

The spelling of 81505340 in words is "eighty-one million, five hundred five thousand, three hundred forty".