2121122220021 has 16 divisors (see below), whose sum is σ = 3591318044800. Its totient is φ = 1212069839904.

The previous prime is 2121122220011. The next prime is 2121122220067. The reversal of 2121122220021 is 1200222211212.

It is a happy number.

2121122220021 is a `hidden beast` number, since 212 + 11 + 222 + 200 + 21 = 666.

It is not a de Polignac number, because 2121122220021 - 2⁷ = 2121122219893 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2121122219976 and 2121122220003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2121122220011) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5611434256 + ... + 5611434633.

It is an arithmetic number, because the mean of its divisors is an integer number (224457377800).

Almost surely, 2^{2121122220021} is an apocalyptic number.

2121122220021 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

2121122220021 is a deficient number, since it is larger than the sum of its proper divisors (1470195824779).

2121122220021 is a wasteful number, since it uses less digits than its factorization.

2121122220021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11222868905 (or 11222868899 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

Adding to 2121122220021 its reverse (1200222211212), we get a palindrome (3321344431233).

The spelling of 2121122220021 in words is "two trillion, one hundred twenty-one billion, one hundred twenty-two million, two hundred twenty thousand, twenty-one".