11958555821 has 4 divisors (see below), whose sum is σ = 11960602044. Its totient is φ = 11956509600.

The previous prime is 11958555781. The next prime is 11958555827. The reversal of 11958555821 is 12855585911.

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 4800549796 + 7158006025 = 69286^2 + 84605^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-11958555821 is a prime.

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 11958555821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11958555827) 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, 1014320 + ... + 1026041.

It is an arithmetic number, because the mean of its divisors is an integer number (2990150511).

Almost surely, 2^11958555821 is an apocalyptic number.

It is an amenable number.

11958555821 is a deficient number, since it is larger than the sum of its proper divisors (2046223).

11958555821 is an equidigital number, since it uses as much as digits as its factorization.

11958555821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2046222.

The product of its digits is 720000, while the sum is 50.

The spelling of 11958555821 in words is "eleven billion, nine hundred fifty-eight million, five hundred fifty-five thousand, eight hundred twenty-one".