11111221000 has 128 divisors (see below), whose sum is σ = 28542533760. Its totient is φ = 4015008000.

The previous prime is 11111220971. The next prime is 11111221001. The reversal of 11111221000 is 12211111.

It is a super-2 number, since 2×11111221000² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (10).

It is not an unprimeable number, because it can be changed into a prime (11111221001) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1789902 + ... + 1796098.

It is an arithmetic number, because the mean of its divisors is an integer number (222988545).

Almost surely, 2^11111221000 is an apocalyptic number.

11111221000 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 11111221000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (14271266880).

11111221000 is an abundant number, since it is smaller than the sum of its proper divisors (17431312760).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

11111221000 is a wasteful number, since it uses less digits than its factorization.

11111221000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6392 (or 6378 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 10.

Adding to 11111221000 its reverse (12211111), we get a palindrome (11123432111).

The spelling of 11111221000 in words is "eleven billion, one hundred eleven million, two hundred twenty-one thousand".