1221120100 has 36 divisors (see below), whose sum is σ = 2664673200. Its totient is φ = 485712160.

The previous prime is 1221120079. The next prime is 1221120107. The reversal of 1221120100 is 10211221.

It is a super-2 number, since 2×1221120100² = 2982268597248020000, which 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 (1221120107) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 16210 + ... + 52009.

It is an arithmetic number, because the mean of its divisors is an integer number (74018700).

Almost surely, 2^1221120100 is an apocalyptic number.

1221120100 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221120100 is an abundant number, since it is smaller than the sum of its proper divisors (1443553100).

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

1221120100 is a wasteful number, since it uses less digits than its factorization.

1221120100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 68412 (or 68405 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 10.

The square root of 1221120100 is about 34944.5288993857. The cubic root of 1221120100 is about 1068.8566410922.

Adding to 1221120100 its reverse (10211221), we get a palindrome (1231331321).

The spelling of 1221120100 in words is "one billion, two hundred twenty-one million, one hundred twenty thousand, one hundred".