1221020011000 has 64 divisors (see below), whose sum is σ = 2864173572000. Its totient is φ = 487213689600.

The previous prime is 1221020010997. The next prime is 1221020011007. The reversal of 1221020011000 is 1100201221.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221020011007) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1083690 + ... + 1901689.

Almost surely, 2^{1221020011000} is an apocalyptic number.

1221020011000 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221020011000 is an abundant number, since it is smaller than the sum of its proper divisors (1643153561000).

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

1221020011000 is a wasteful number, since it uses less digits than its factorization.

1221020011000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2985809 (or 2985795 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 10.

Adding to 1221020011000 its reverse (1100201221), we get a palindrome (1222120212221).

The spelling of 1221020011000 in words is "one trillion, two hundred twenty-one billion, twenty million, eleven thousand".