1221221101020 has 48 divisors (see below), whose sum is σ = 3420276965280. Its totient is φ = 325577257216.

The previous prime is 1221221100977. The next prime is 1221221101039. The reversal of 1221221101020 is 201011221221.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2311887 + ... + 2790566.

It is an arithmetic number, because the mean of its divisors is an integer number (71255770110).

Almost surely, 2^{1221221101020} is an apocalyptic number.

1221221101020 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221221101020 is an abundant number, since it is smaller than the sum of its proper divisors (2199055864260).

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

1221221101020 is a wasteful number, since it uses less digits than its factorization.

1221221101020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5106454 (or 5106452 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 15.

Adding to 1221221101020 its reverse (201011221221), we get a palindrome (1422232322241).

The spelling of 1221221101020 in words is "one trillion, two hundred twenty-one billion, two hundred twenty-one million, one hundred one thousand, twenty".