1221013000020 has 384 divisors, whose sum is σ = 3926545072128. Its totient is φ = 280617779200.

The previous prime is 1221012999991. The next prime is 1221013000021. The reversal of 1221013000020 is 200003101221.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221013000021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 1023480544 + ... + 1023481736.

It is an arithmetic number, because the mean of its divisors is an integer number (10225377792).

Almost surely, 2^{1221013000020} is an apocalyptic number.

1221013000020 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 1221013000020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1963272536064).

1221013000020 is an abundant number, since it is smaller than the sum of its proper divisors (2705532072108).

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

1221013000020 is a wasteful number, since it uses less digits than its factorization.

1221013000020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1783 (or 1781 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 12.

Adding to 1221013000020 its reverse (200003101221), we get a palindrome (1421016101241).

The spelling of 1221013000020 in words is "one trillion, two hundred twenty-one billion, thirteen million, twenty", and thus it is an aban number.