121221001020 has 72 divisors (see below), whose sum is σ = 394834127184. Its totient is φ = 27707656704.

The previous prime is 121221001009. The next prime is 121221001073. The reversal of 121221001020 is 20100122121.

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

It is a junction number, because it is equal to n+sod(n) for n = 121221000987 and 121221001005.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 20612877 + ... + 20618756.

It is an arithmetic number, because the mean of its divisors is an integer number (5483807322).

Almost surely, 2^121221001020 is an apocalyptic number.

121221001020 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

121221001020 is an abundant number, since it is smaller than the sum of its proper divisors (273613126164).

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

121221001020 is a wasteful number, since it uses less digits than its factorization.

121221001020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41231659 (or 41231650 counting only the distinct ones).

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

Adding to 121221001020 its reverse (20100122121), we get a palindrome (141321123141).

The spelling of 121221001020 in words is "one hundred twenty-one billion, two hundred twenty-one million, one thousand, twenty".