81505360 has 20 divisors (see below), whose sum is σ = 189500148. Its totient is φ = 32602112.

The previous prime is 81505357. The next prime is 81505363. The reversal of 81505360 is 6350518.

It is an interprime number because it is at equal distance from previous prime (81505357) and next prime (81505363).

It can be written as a sum of positive squares in 2 ways, for example, as 29550096 + 51955264 = 5436^2 + 7208^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81505363) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 509329 + ... + 509488.

Almost surely, 2^81505360 is an apocalyptic number.

81505360 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81505360 is an abundant number, since it is smaller than the sum of its proper divisors (107994788).

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

81505360 is a wasteful number, since it uses less digits than its factorization.

81505360 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1018830 (or 1018824 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 28.

The square root of 81505360 is about 9028.0319006969. The cubic root of 81505360 is about 433.5728275071.

Adding to 81505360 its reverse (6350518), we get a palindrome (87855878).

The spelling of 81505360 in words is "eighty-one million, five hundred five thousand, three hundred sixty".