1221200121220 has 48 divisors (see below), whose sum is σ = 2575878904368. Its totient is φ = 486317629440.

The previous prime is 1221200121173. The next prime is 1221200121223. The reversal of 1221200121220 is 221210021221.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 83154949956 + 1138045171264 = 288366^2 + 1066792^2 .

It is a junction number, because it is equal to n+sod(n) for n = 1221200121194 and 1221200121203.

It is not an unprimeable number, because it can be changed into a prime (1221200121223) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 18248862 + ... + 18315658.

It is an arithmetic number, because the mean of its divisors is an integer number (53664143841).

Almost surely, 2^{1221200121220} is an apocalyptic number.

1221200121220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221200121220 is an abundant number, since it is smaller than the sum of its proper divisors (1354678783148).

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

1221200121220 is a wasteful number, since it uses less digits than its factorization.

1221200121220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 70840 (or 70838 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 1221200121220 its reverse (221210021221), we get a palindrome (1442410142441).

Subtracting from 1221200121220 its reverse (221210021221), we obtain a palindrome (999990099999).

It can be divided in two parts, 12212001 and 21220, that added together give a palindrome (12233221).

The spelling of 1221200121220 in words is "one trillion, two hundred twenty-one billion, two hundred million, one hundred twenty-one thousand, two hundred twenty".