2121021205 has 24 divisors (see below), whose sum is σ = 2723202072. Its totient is φ = 1585391616.

The previous prime is 2121021197. The next prime is 2121021223. The reversal of 2121021205 is 5021201212.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 312900721 + 1808120484 = 17689^2 + 42522^2 .

It is not a de Polignac number, because 2121021205 - 2³ = 2121021197 is a prime.

It is a Duffinian number.

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, 123717 + ... + 139813.

It is an arithmetic number, because the mean of its divisors is an integer number (113466753).

Almost surely, 2^2121021205 is an apocalyptic number.

It is an amenable number.

2121021205 is a deficient number, since it is larger than the sum of its proper divisors (602180867).

2121021205 is a wasteful number, since it uses less digits than its factorization.

2121021205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16213 (or 16194 counting only the distinct ones).

The product of its (nonzero) digits is 80, while the sum is 16.

The square root of 2121021205 is about 46054.5459753975. The cubic root of 2121021205 is about 1284.8378938265.

Adding to 2121021205 its reverse (5021201212), we get a palindrome (7142222417).

The spelling of 2121021205 in words is "two billion, one hundred twenty-one million, twenty-one thousand, two hundred five".