1211221000020 has 72 divisors (see below), whose sum is σ = 3512397024864. Its totient is φ = 311854589312.

The previous prime is 1211220999883. The next prime is 1211221000021. The reversal of 1211221000020 is 200001221121.

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 (1211221000021) 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 23 ways as a sum of consecutive naturals, for example, 11951334 + ... + 12052253.

It is an arithmetic number, because the mean of its divisors is an integer number (48783292012).

Almost surely, 2^{1211221000020} is an apocalyptic number.

1211221000020 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1211221000020 is an abundant number, since it is smaller than the sum of its proper divisors (2301176024844).

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

1211221000020 is a wasteful number, since it uses less digits than its factorization.

1211221000020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24003657 (or 24003626 counting only the distinct ones).

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

Adding to 1211221000020 its reverse (200001221121), we get a palindrome (1411222221141).

The spelling of 1211221000020 in words is "one trillion, two hundred eleven billion, two hundred twenty-one million, twenty", and thus it is an aban number.