81987016 has 16 divisors (see below), whose sum is σ = 153832140. Its totient is φ = 40965120.

The previous prime is 81987011. The next prime is 81987041. The reversal of 81987016 is 61078918.

It can be written as a sum of positive squares in 2 ways, for example, as 81974916 + 12100 = 9054^2 + 110^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 81987016.

It is not an unprimeable number, because it can be changed into a prime (81987011) 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 3 ways as a sum of consecutive naturals, for example, 13596 + ... + 18676.

Almost surely, 2^81987016 is an apocalyptic number.

It is an amenable number.

81987016 is a deficient number, since it is larger than the sum of its proper divisors (71845124).

81987016 is a wasteful number, since it uses less digits than its factorization.

81987016 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7104 (or 7100 counting only the distinct ones).

The product of its (nonzero) digits is 24192, while the sum is 40.

The square root of 81987016 is about 9054.6681882883. The cubic root of 81987016 is about 434.4252169813.

The spelling of 81987016 in words is "eighty-one million, nine hundred eighty-seven thousand, sixteen".