11945821309 has 4 divisors (see below), whose sum is σ = 12068974204. Its totient is φ = 11822668416.

The previous prime is 11945821291. The next prime is 11945821313. The reversal of 11945821309 is 90312854911.

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 9101732409 + 2844088900 = 95403^2 + 53330^2 .

It is a cyclic number.

It is not a de Polignac number, because 11945821309 - 2²⁷ = 11811603581 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 (11945821399) 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, 61576302 + ... + 61576495.

It is an arithmetic number, because the mean of its divisors is an integer number (3017243551).

Almost surely, 2^11945821309 is an apocalyptic number.

It is an amenable number.

11945821309 is a deficient number, since it is larger than the sum of its proper divisors (123152895).

11945821309 is an equidigital number, since it uses as much as digits as its factorization.

11945821309 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 123152894.

The product of its (nonzero) digits is 77760, while the sum is 43.

The spelling of 11945821309 in words is "eleven billion, nine hundred forty-five million, eight hundred twenty-one thousand, three hundred nine".