1221000211200 has 864 divisors, whose sum is σ = 5070620459520. Its totient is φ = 251353497600.

The previous prime is 1221000211117. The next prime is 1221000211201. The reversal of 1221000211200 is 21120001221.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is not an unprimeable number, because it can be changed into a prime (1221000211201) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 161141812 + ... + 161149388.

It is an arithmetic number, because the mean of its divisors is an integer number (5868773680).

Almost surely, 2^{1221000211200} is an apocalyptic number.

1221000211200 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 1221000211200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2535310229760).

1221000211200 is an abundant number, since it is smaller than the sum of its proper divisors (3849620248320).

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

1221000211200 is a wasteful number, since it uses less digits than its factorization.

1221000211200 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7733 (or 7714 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 1221000211200 its reverse (21120001221), we get a palindrome (1242120212421).

It can be divided in two parts, 122100021 and 1200, that added together give a palindrome (122101221).

The spelling of 1221000211200 in words is "one trillion, two hundred twenty-one billion, two hundred eleven thousand, two hundred".