1221200012100 has 72 divisors (see below), whose sum is σ = 3686962144320. Its totient is φ = 311494494080.

The previous prime is 1221200012099. The next prime is 1221200012113. The reversal of 1221200012100 is 12100021221.

It is a super-3 number, since 3×1221200012100³ (a number of 37 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 88485855 + ... + 88499654.

It is an arithmetic number, because the mean of its divisors is an integer number (51207807560).

Almost surely, 2^{1221200012100} is an apocalyptic number.

1221200012100 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221200012100 is an abundant number, since it is smaller than the sum of its proper divisors (2465762132220).

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

1221200012100 is a wasteful number, since it uses less digits than its factorization.

1221200012100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 176985549 (or 176985542 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 1221200012100 its reverse (12100021221), we get a palindrome (1233300033321).

The spelling of 1221200012100 in words is "one trillion, two hundred twenty-one billion, two hundred million, twelve thousand, one hundred".