81516340 has 12 divisors (see below), whose sum is σ = 171184356. Its totient is φ = 32606528.

The previous prime is 81516319. The next prime is 81516341. The reversal of 81516340 is 4361518.

It can be written as a sum of positive squares in 2 ways, for example, as 12194064 + 69322276 = 3492^2 + 8326^2 .

It is a junction number, because it is equal to n+sod(n) for n = 81516299 and 81516308.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81516341) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2037889 + ... + 2037928.

It is an arithmetic number, because the mean of its divisors is an integer number (14265363).

Almost surely, 2^81516340 is an apocalyptic number.

It is an amenable number.

81516340 is an abundant number, since it is smaller than the sum of its proper divisors (89668016).

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

81516340 is a wasteful number, since it uses less digits than its factorization.

81516340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4075826 (or 4075824 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 28.

The square root of 81516340 is about 9028.6399861773. The cubic root of 81516340 is about 433.5922962303.

Adding to 81516340 its reverse (4361518), we get a palindrome (85877858).

The spelling of 81516340 in words is "eighty-one million, five hundred sixteen thousand, three hundred forty".