1221000010020 has 144 divisors (see below), whose sum is σ = 4233138594048. Its totient is φ = 279063394560.

The previous prime is 1221000010019. The next prime is 1221000010031. The reversal of 1221000010020 is 200100001221.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a junction number, because it is equal to n+sod(n) for n = 1221000009984 and 1221000010011.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 19714542 + ... + 19776378.

It is an arithmetic number, because the mean of its divisors is an integer number (29396795792).

Almost surely, 2^{1221000010020} is an apocalyptic number.

1221000010020 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221000010020 is an abundant number, since it is smaller than the sum of its proper divisors (3012138584028).

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

1221000010020 is a wasteful number, since it uses less digits than its factorization.

1221000010020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77530 (or 77525 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

Adding to 1221000010020 its reverse (200100001221), we get a palindrome (1421100011241).

The spelling of 1221000010020 in words is "one trillion, two hundred twenty-one billion, ten thousand, twenty".