87821684681 has 4 divisors (see below), whose sum is σ = 87866746500. Its totient is φ = 87776622864.

The previous prime is 87821684663. The next prime is 87821684747. The reversal of 87821684681 is 18648612878.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 69463873600 + 18357811081 = 263560^2 + 135491^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-87821684681 is a prime.

It is a super-2 number, since 2×87821684681² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 87821684681.

It is not an unprimeable number, because it can be changed into a prime (87821684641) 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, 22527986 + ... + 22531883.

It is an arithmetic number, because the mean of its divisors is an integer number (21966686625).

Almost surely, 2^87821684681 is an apocalyptic number.

It is an amenable number.

87821684681 is a deficient number, since it is larger than the sum of its proper divisors (45061819).

87821684681 is a wasteful number, since it uses less digits than its factorization.

87821684681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45061818.

The product of its digits is 8257536, while the sum is 59.

The spelling of 87821684681 in words is "eighty-seven billion, eight hundred twenty-one million, six hundred eighty-four thousand, six hundred eighty-one".