1221200020000 has 120 divisors (see below), whose sum is σ = 3016813257612. Its totient is φ = 486451200000.

The previous prime is 1221200019953. The next prime is 1221200020009. The reversal of 1221200020000 is 200021221.

It can be written as a sum of positive squares in 10 ways, for example, as 107896482576 + 1113303537424 = 328476^2 + 1055132^2 .

It is a Harshad number since it is a multiple of its sum of digits (10).

It is not an unprimeable number, because it can be changed into a prime (1221200020009) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 4693320 + ... + 4946680.

Almost surely, 2^{1221200020000} is an apocalyptic number.

1221200020000 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 1221200020000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1508406628806).

1221200020000 is an abundant number, since it is smaller than the sum of its proper divisors (1795613237612).

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

1221200020000 is an equidigital number, since it uses as much as digits as its factorization.

1221200020000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 253632 (or 253609 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 10.

Adding to 1221200020000 its reverse (200021221), we get a palindrome (1221400041221).

The spelling of 1221200020000 in words is "one trillion, two hundred twenty-one billion, two hundred million, twenty thousand".