1221123212100 has 216 divisors, whose sum is σ = 4182562736352. Its totient is φ = 295529241600.

The previous prime is 1221123212069. The next prime is 1221123212119. The reversal of 1221123212100 is 12123211221.

1221123212100 is a `hidden beast` number, since 1 + 22 + 112 + 321 + 210 + 0 = 666.

It is a super-2 number, since 2×1221123212100² (a number of 25 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 5766699 + ... + 5974701.

It is an arithmetic number, because the mean of its divisors is an integer number (19363716372).

Almost surely, 2^{1221123212100} is an apocalyptic number.

1221123212100 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 1221123212100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2091281368176).

1221123212100 is an abundant number, since it is smaller than the sum of its proper divisors (2961439524252).

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

1221123212100 is a wasteful number, since it uses less digits than its factorization.

1221123212100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 208627 (or 208617 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 18.

Adding to 1221123212100 its reverse (12123211221), we get a palindrome (1233246423321).

The spelling of 1221123212100 in words is "one trillion, two hundred twenty-one billion, one hundred twenty-three million, two hundred twelve thousand, one hundred".