2121021221 has 6 divisors (see below), whose sum is σ = 2331370566. Its totient is φ = 1928201000.

The previous prime is 2121021197. The next prime is 2121021223. The reversal of 2121021221 is 1221201212.

It can be written as a sum of positive squares in only one way, i.e., 1612022500 + 508998721 = 40150^2 + 22561^2 .

It is a de Polignac number, because none of the positive numbers 2^k-2121021221 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2121021196 and 2121021205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2121021223) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 8764430 + ... + 8764671.

It is an arithmetic number, because the mean of its divisors is an integer number (388561761).

Almost surely, 2^2121021221 is an apocalyptic number.

It is an amenable number.

2121021221 is a deficient number, since it is larger than the sum of its proper divisors (210349345).

2121021221 is a wasteful number, since it uses less digits than its factorization.

2121021221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17529123 (or 17529112 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 14.

The square root of 2121021221 is about 46054.5461491045. The cubic root of 2121021221 is about 1284.8378970572.

Adding to 2121021221 its reverse (1221201212), we get a palindrome (3342222433).

Subtracting from 2121021221 its reverse (1221201212), we obtain a square (899820009 = 29997²).

The spelling of 2121021221 in words is "two billion, one hundred twenty-one million, twenty-one thousand, two hundred twenty-one".