21185836887 has 4 divisors (see below), whose sum is σ = 28247782520. Its totient is φ = 14123891256.

The previous prime is 21185836877. The next prime is 21185836909. The reversal of 21185836887 is 78863858112.

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

It is not a de Polignac number, because 21185836887 - 2⁶ = 21185836823 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21185836877) 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, 3530972812 + ... + 3530972817.

It is an arithmetic number, because the mean of its divisors is an integer number (7061945630).

Almost surely, 2^21185836887 is an apocalyptic number.

21185836887 is a deficient number, since it is larger than the sum of its proper divisors (7061945633).

21185836887 is an equidigital number, since it uses as much as digits as its factorization.

21185836887 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7061945632.

The product of its digits is 5160960, while the sum is 57.

The spelling of 21185836887 in words is "twenty-one billion, one hundred eighty-five million, eight hundred thirty-six thousand, eight hundred eighty-seven".