1221111000 has 384 divisors, whose sum is σ = 4485124800. Its totient is φ = 298598400.

The previous prime is 1221110983. The next prime is 1221111007. The reversal of 1221111000 is 1111221.

It is a happy number.

It is a super-2 number, since 2×1221111000² = 2982224148642000000, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221111007) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 6326904 + ... + 6327096.

Almost surely, 2^1221111000 is an apocalyptic number.

1221111000 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 1221111000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2242562400).

1221111000 is an abundant number, since it is smaller than the sum of its proper divisors (3264013800).

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

1221111000 is a wasteful number, since it uses less digits than its factorization.

1221111000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 276 (or 259 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 9.

The square root of 1221111000 is about 34944.3986927805. The cubic root of 1221111000 is about 1068.8539859835.

Adding to 1221111000 its reverse (1111221), we get a palindrome (1222222221).

The spelling of 1221111000 in words is "one billion, two hundred twenty-one million, one hundred eleven thousand".