4221121021 has 4 divisors (see below), whose sum is σ = 4545822652. Its totient is φ = 3896419392.

The previous prime is 4221121019. The next prime is 4221121031. The reversal of 4221121021 is 1201211224.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2142764100 + 2078356921 = 46290^2 + 45589^2 .

It is a cyclic number.

It is not a de Polignac number, because 4221121021 - 2¹ = 4221121019 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 4221120986 and 4221121004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (4221121031) 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, 162350796 + ... + 162350821.

It is an arithmetic number, because the mean of its divisors is an integer number (1136455663).

Almost surely, 2^4221121021 is an apocalyptic number.

It is an amenable number.

4221121021 is a deficient number, since it is larger than the sum of its proper divisors (324701631).

4221121021 is a wasteful number, since it uses less digits than its factorization.

4221121021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 324701630.

The product of its (nonzero) digits is 64, while the sum is 16.

The square root of 4221121021 is about 64970.1548482070. The cubic root of 4221121021 is about 1616.1286695666.

Adding to 4221121021 its reverse (1201211224), we get a palindrome (5422332245).

The spelling of 4221121021 in words is "four billion, two hundred twenty-one million, one hundred twenty-one thousand, twenty-one".