1221120221000 has 64 divisors (see below), whose sum is σ = 2859338692080. Its totient is φ = 488120332800.

The previous prime is 1221120220993. The next prime is 1221120221003. The reversal of 1221120221000 is 1220211221.

It can be written as a sum of positive squares in 8 ways, for example, as 77465362276 + 1143654858724 = 278326^2 + 1069418^2 .

It is a super-2 number, since 2×1221120221000² (a number of 25 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1221120221003) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1084052 + ... + 1901948.

Almost surely, 2^{1221120221000} is an apocalyptic number.

1221120221000 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 1221120221000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1429669346040).

1221120221000 is an abundant number, since it is smaller than the sum of its proper divisors (1638218471080).

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

1221120221000 is a wasteful number, since it uses less digits than its factorization.

1221120221000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 819411 (or 819397 counting only the distinct ones).

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

Adding to 1221120221000 its reverse (1220211221), we get a palindrome (1222340432221).

The spelling of 1221120221000 in words is "one trillion, two hundred twenty-one billion, one hundred twenty million, two hundred twenty-one thousand".