21311106587 has 4 divisors (see below), whose sum is σ = 21328971240. Its totient is φ = 21293241936.

The previous prime is 21311106569. The next prime is 21311106599. The reversal of 21311106587 is 78560111312.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21311106587 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21311106787) 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, 8930537 + ... + 8932922.

It is an arithmetic number, because the mean of its divisors is an integer number (5332242810).

Almost surely, 2^21311106587 is an apocalyptic number.

21311106587 is a deficient number, since it is larger than the sum of its proper divisors (17864653).

21311106587 is a wasteful number, since it uses less digits than its factorization.

21311106587 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17864652.

The product of its (nonzero) digits is 10080, while the sum is 35.

Adding to 21311106587 its reverse (78560111312), we get a palindrome (99871217899).

The spelling of 21311106587 in words is "twenty-one billion, three hundred eleven million, one hundred six thousand, five hundred eighty-seven".