1221111221200 has 120 divisors (see below), whose sum is σ = 3194890435800. Its totient is φ = 445805690880.

The previous prime is 1221111221191. The next prime is 1221111221219. The reversal of 1221111221200 is 21221111221.

It can be written as a sum of positive squares in 12 ways, for example, as 551947956624 + 669163264576 = 742932^2 + 818024^2 .

It is a super-2 number, since 2×1221111221200² (a number of 25 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (16).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 856465 + ... + 1782064.

It is an arithmetic number, because the mean of its divisors is an integer number (26624086965).

Almost surely, 2^{1221111221200} is an apocalyptic number.

1221111221200 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221111221200 is an abundant number, since it is smaller than the sum of its proper divisors (1973779214600).

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

1221111221200 is a wasteful number, since it uses less digits than its factorization.

1221111221200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2638649 (or 2638638 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 16.

Adding to 1221111221200 its reverse (21221111221), we get a palindrome (1242332332421).

The spelling of 1221111221200 in words is "one trillion, two hundred twenty-one billion, one hundred eleven million, two hundred twenty-one thousand, two hundred".