11687215821 has 4 divisors (see below), whose sum is σ = 15582954432. Its totient is φ = 7791477212.

The previous prime is 11687215801. The next prime is 11687215823. The reversal of 11687215821 is 12851278611.

11687215821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 11687215821 - 2²⁶ = 11620106957 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11687215823) 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, 1947869301 + ... + 1947869306.

It is an arithmetic number, because the mean of its divisors is an integer number (3895738608).

Almost surely, 2^11687215821 is an apocalyptic number.

It is an amenable number.

11687215821 is a deficient number, since it is larger than the sum of its proper divisors (3895738611).

11687215821 is an equidigital number, since it uses as much as digits as its factorization.

11687215821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3895738610.

The product of its digits is 53760, while the sum is 42.

The spelling of 11687215821 in words is "eleven billion, six hundred eighty-seven million, two hundred fifteen thousand, eight hundred twenty-one".