1221022221000 has 128 divisors (see below), whose sum is σ = 3816289900800. Its totient is φ = 325033228800.

The previous prime is 1221022220983. The next prime is 1221022221049. The reversal of 1221022221000 is 1222201221.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1349349 + ... + 2064651.

It is an arithmetic number, because the mean of its divisors is an integer number (29814764850).

Almost surely, 2^{1221022221000} is an apocalyptic number.

1221022221000 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 1221022221000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1908144950400).

1221022221000 is an abundant number, since it is smaller than the sum of its proper divisors (2595267679800).

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

1221022221000 is a wasteful number, since it uses less digits than its factorization.

1221022221000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 715896 (or 715882 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 15.

Adding to 1221022221000 its reverse (1222201221), we get a palindrome (1222244422221).

The spelling of 1221022221000 in words is "one trillion, two hundred twenty-one billion, twenty-two million, two hundred twenty-one thousand".