2121404021 has 4 divisors (see below), whose sum is σ = 2314258944. Its totient is φ = 1928549100.

The previous prime is 2121404003. The next prime is 2121404053. The reversal of 2121404021 is 1204041212.

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 2121404021 - 2³⁰ = 1047662197 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2121404071) 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, 96427445 + ... + 96427466.

It is an arithmetic number, because the mean of its divisors is an integer number (578564736).

Almost surely, 2^2121404021 is an apocalyptic number.

It is an amenable number.

2121404021 is a deficient number, since it is larger than the sum of its proper divisors (192854923).

2121404021 is a wasteful number, since it uses less digits than its factorization.

2121404021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 192854922.

The product of its (nonzero) digits is 128, while the sum is 17.

The square root of 2121404021 is about 46058.7019031149. The cubic root of 2121404021 is about 1284.9151878699.

Adding to 2121404021 its reverse (1204041212), we get a palindrome (3325445233).

The spelling of 2121404021 in words is "two billion, one hundred twenty-one million, four hundred four thousand, twenty-one".