1221100221000 has 128 divisors (see below), whose sum is σ = 4156181228160. Its totient is φ = 296024288000.

The previous prime is 1221100220981. The next prime is 1221100221001. The reversal of 1221100221000 is 1220011221.

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 (1221100221001) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 18468519 + ... + 18534518.

It is an arithmetic number, because the mean of its divisors is an integer number (32470165845).

Almost surely, 2^{1221100221000} is an apocalyptic number.

1221100221000 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221100221000 is an abundant number, since it is smaller than the sum of its proper divisors (2935081007160).

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

1221100221000 is a wasteful number, since it uses less digits than its factorization.

1221100221000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37003072 (or 37003058 counting only the distinct ones).

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

Adding to 1221100221000 its reverse (1220011221), we get a palindrome (1222320232221).

The spelling of 1221100221000 in words is "one trillion, two hundred twenty-one billion, one hundred million, two hundred twenty-one thousand".