11181221428 has 48 divisors (see below), whose sum is σ = 21318920784. Its totient is φ = 5100318720.

The previous prime is 11181221423. The next prime is 11181221461. The reversal of 11181221428 is 82412218111.

It can be written as a sum of positive squares in 8 ways, for example, as 89340304 + 11091881124 = 9452^2 + 105318^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 11181221428.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11181221423) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5956026 + ... + 5957902.

It is an arithmetic number, because the mean of its divisors is an integer number (444144183).

Almost surely, 2^11181221428 is an apocalyptic number.

It is an amenable number.

11181221428 is a deficient number, since it is larger than the sum of its proper divisors (10137699356).

11181221428 is a wasteful number, since it uses less digits than its factorization.

11181221428 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3172 (or 3170 counting only the distinct ones).

The product of its digits is 2048, while the sum is 31.

Adding to 11181221428 its reverse (82412218111), we get a palindrome (93593439539).

The spelling of 11181221428 in words is "eleven billion, one hundred eighty-one million, two hundred twenty-one thousand, four hundred twenty-eight".