11821491909 has 24 divisors (see below), whose sum is σ = 18089554392. Its totient is φ = 7413457920.

The previous prime is 11821491883. The next prime is 11821491923. The reversal of 11821491909 is 90919412811.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 1509089409 + 10312402500 = 38847^2 + 101550^2 .

It is not a de Polignac number, because 11821491909 - 2¹³ = 11821483717 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11821491109) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 282289 + ... + 321449.

It is an arithmetic number, because the mean of its divisors is an integer number (753731433).

Almost surely, 2^11821491909 is an apocalyptic number.

It is an amenable number.

11821491909 is a deficient number, since it is larger than the sum of its proper divisors (6268062483).

11821491909 is a wasteful number, since it uses less digits than its factorization.

11821491909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41157 (or 41154 counting only the distinct ones).

The product of its (nonzero) digits is 46656, while the sum is 45.

The spelling of 11821491909 in words is "eleven billion, eight hundred twenty-one million, four hundred ninety-one thousand, nine hundred nine".