1221121100 has 36 divisors (see below), whose sum is σ = 2706222624. Its totient is φ = 478054080.

The previous prime is 1221121073. The next prime is 1221121117. The reversal of 1221121100 is 11211221.

It is a super-2 number, since 2×1221121100² = 2982273481730420000, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 125207 + ... + 134606.

Almost surely, 2^1221121100 is an apocalyptic number.

1221121100 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221121100 is an abundant number, since it is smaller than the sum of its proper divisors (1485101524).

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

1221121100 is a wasteful number, since it uses less digits than its factorization.

1221121100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 259874 (or 259867 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 11.

The square root of 1221121100 is about 34944.5432077742. The cubic root of 1221121100 is about 1068.8569328615.

Adding to 1221121100 its reverse (11211221), we get a palindrome (1232332321).

It can be divided in two parts, 1221121 and 100, that added together give a palindrome (1221221).

The spelling of 1221121100 in words is "one billion, two hundred twenty-one million, one hundred twenty-one thousand, one hundred".