121221220100 has 72 divisors (see below), whose sum is σ = 268395378888. Its totient is φ = 47513088000.

The previous prime is 121221220091. The next prime is 121221220111. The reversal of 121221220100 is 1022122121.

It can be written as a sum of positive squares in 12 ways, for example, as 1160356096 + 120060864004 = 34064^2 + 346498^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 917834 + ... + 1041566.

Almost surely, 2^121221220100 is an apocalyptic number.

121221220100 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 121221220100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (134197689444).

121221220100 is an abundant number, since it is smaller than the sum of its proper divisors (147174158788).

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

121221220100 is a wasteful number, since it uses less digits than its factorization.

121221220100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 123945 (or 123938 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 121221220100 its reverse (1022122121), we get a palindrome (122243342221).

The spelling of 121221220100 in words is "one hundred twenty-one billion, two hundred twenty-one million, two hundred twenty thousand, one hundred".