2121020021 has 4 divisors (see below), whose sum is σ = 2170346112. Its totient is φ = 2071693932.

The previous prime is 2121019997. The next prime is 2121020039. The reversal of 2121020021 is 1200201212.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 2121020021 - 2¹⁴ = 2121003637 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2121019984 and 2121020011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2121020051) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24662981 + ... + 24663066.

It is an arithmetic number, because the mean of its divisors is an integer number (542586528).

Almost surely, 2^2121020021 is an apocalyptic number.

It is an amenable number.

2121020021 is a deficient number, since it is larger than the sum of its proper divisors (49326091).

2121020021 is an equidigital number, since it uses as much as digits as its factorization.

2121020021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49326090.

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

The square root of 2121020021 is about 46054.5331210729. The cubic root of 2121020021 is about 1284.8376547517.

Adding to 2121020021 its reverse (1200201212), we get a palindrome (3321221233).

The spelling of 2121020021 in words is "two billion, one hundred twenty-one million, twenty thousand, twenty-one".