81516020 has 24 divisors (see below), whose sum is σ = 181254024. Its totient is φ = 30688256.

The previous prime is 81516011. The next prime is 81516041. The reversal of 81516020 is 2061518.

It can be written as a sum of positive squares in 4 ways, for example, as 1628176 + 79887844 = 1276^2 + 8938^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 119537 + ... + 120216.

It is an arithmetic number, because the mean of its divisors is an integer number (7552251).

Almost surely, 2^81516020 is an apocalyptic number.

It is an amenable number.

81516020 is an abundant number, since it is smaller than the sum of its proper divisors (99738004).

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

81516020 is a wasteful number, since it uses less digits than its factorization.

81516020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 239779 (or 239777 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 23.

The square root of 81516020 is about 9028.6222647755. The cubic root of 81516020 is about 433.5917288605.

Adding to 81516020 its reverse (2061518), we get a palindrome (83577538).

The spelling of 81516020 in words is "eighty-one million, five hundred sixteen thousand, twenty".