1221312200 has 96 divisors (see below), whose sum is σ = 2900439360. Its totient is φ = 478176000.

The previous prime is 1221312199. The next prime is 1221312203. The reversal of 1221312200 is 22131221.

It is a happy number.

1221312200 is digitally balanced in base 6, because in such base it contains all the possibile digits an equal number of times.

It is not an unprimeable number, because it can be changed into a prime (1221312203) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2080307 + ... + 2080893.

It is an arithmetic number, because the mean of its divisors is an integer number (30212910).

Almost surely, 2^1221312200 is an apocalyptic number.

1221312200 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 1221312200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1450219680).

1221312200 is an abundant number, since it is smaller than the sum of its proper divisors (1679127160).

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

1221312200 is a wasteful number, since it uses less digits than its factorization.

1221312200 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 807 (or 798 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 14.

The square root of 1221312200 is about 34947.2774332994. The cubic root of 1221312200 is about 1068.9126870658.

Adding to 1221312200 its reverse (22131221), we get a palindrome (1243443421).

The spelling of 1221312200 in words is "one billion, two hundred twenty-one million, three hundred twelve thousand, two hundred".