1211221001000 has 64 divisors (see below), whose sum is σ = 2835618786000. Its totient is φ = 484255641600.

The previous prime is 1211221000993. The next prime is 1211221001021. The reversal of 1211221001000 is 1001221121.

It can be written as a sum of positive squares in 8 ways, for example, as 535698103396 + 675522897604 = 731914^2 + 821902^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1799096 + ... + 2378904.

Almost surely, 2^{1211221001000} is an apocalyptic number.

1211221001000 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 1211221001000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1417809393000).

1211221001000 is an abundant number, since it is smaller than the sum of its proper divisors (1624397785000).

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

1211221001000 is a wasteful number, since it uses less digits than its factorization.

1211221001000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 581919 (or 581905 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 11.

Adding to 1211221001000 its reverse (1001221121), we get a palindrome (1212222222121).

The spelling of 1211221001000 in words is "one trillion, two hundred eleven billion, two hundred twenty-one million, one thousand".