1221020100020 has 96 divisors (see below), whose sum is σ = 3073026297600. Its totient is φ = 398662677504.

The previous prime is 1221020099993. The next prime is 1221020100037. The reversal of 1221020100020 is 200010201221.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 1221020099974 and 1221020100010.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1763510 + ... + 2356269.

It is an arithmetic number, because the mean of its divisors is an integer number (32010690600).

Almost surely, 2^{1221020100020} is an apocalyptic number.

1221020100020 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221020100020 is an abundant number, since it is smaller than the sum of its proper divisors (1852006197580).

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

1221020100020 is a wasteful number, since it uses less digits than its factorization.

1221020100020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4119897 (or 4119895 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 11.

Adding to 1221020100020 its reverse (200010201221), we get a palindrome (1421030301241).

The spelling of 1221020100020 in words is "one trillion, two hundred twenty-one billion, twenty million, one hundred thousand, twenty".