2121310021 has 4 divisors (see below), whose sum is σ = 2122160032. Its totient is φ = 2120460012.

The previous prime is 2121310019. The next prime is 2121310027. The reversal of 2121310021 is 1200131212.

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 2121310021 - 2¹ = 2121310019 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2121309983 and 2121310010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2121310027) 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, 421251 + ... + 426256.

It is an arithmetic number, because the mean of its divisors is an integer number (530540008).

Almost surely, 2^2121310021 is an apocalyptic number.

It is an amenable number.

2121310021 is a deficient number, since it is larger than the sum of its proper divisors (850011).

2121310021 is an equidigital number, since it uses as much as digits as its factorization.

2121310021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 850010.

The product of its (nonzero) digits is 24, while the sum is 13.

The square root of 2121310021 is about 46057.6814548887. The cubic root of 2121310021 is about 1284.8962092735.

Adding to 2121310021 its reverse (1200131212), we get a palindrome (3321441233).

The spelling of 2121310021 in words is "two billion, one hundred twenty-one million, three hundred ten thousand, twenty-one".