21173813587 has 4 divisors (see below), whose sum is σ = 21903945120. Its totient is φ = 20443682056.

The previous prime is 21173813569. The next prime is 21173813659. The reversal of 21173813587 is 78531837112.

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

It is a cyclic number.

It is not a de Polignac number, because 21173813587 - 2¹¹ = 21173811539 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21173813987) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 365065723 + ... + 365065780.

It is an arithmetic number, because the mean of its divisors is an integer number (5475986280).

Almost surely, 2^21173813587 is an apocalyptic number.

21173813587 is a deficient number, since it is larger than the sum of its proper divisors (730131533).

21173813587 is an equidigital number, since it uses as much as digits as its factorization.

21173813587 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 730131532.

The product of its digits is 282240, while the sum is 46.

The spelling of 21173813587 in words is "twenty-one billion, one hundred seventy-three million, eight hundred thirteen thousand, five hundred eighty-seven".