2104221521 has 4 divisors (see below), whose sum is σ = 2104319844. Its totient is φ = 2104123200.

The previous prime is 2104221491. The next prime is 2104221547. The reversal of 2104221521 is 1251224012.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 360240400 + 1743981121 = 18980^2 + 41761^2 .

It is a cyclic number.

It is not a de Polignac number, because 2104221521 - 2¹⁰ = 2104220497 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2104221493 and 2104221502.

It is not an unprimeable number, because it can be changed into a prime (2104221551) 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, 1940 + ... + 64901.

It is an arithmetic number, because the mean of its divisors is an integer number (526079961).

Almost surely, 2^2104221521 is an apocalyptic number.

It is an amenable number.

2104221521 is a deficient number, since it is larger than the sum of its proper divisors (98323).

2104221521 is an equidigital number, since it uses as much as digits as its factorization.

2104221521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 98322.

The product of its (nonzero) digits is 320, while the sum is 20.

The square root of 2104221521 is about 45871.7943948130. The cubic root of 2104221521 is about 1281.4366845773.

Adding to 2104221521 its reverse (1251224012), we get a palindrome (3355445533).

The spelling of 2104221521 in words is "two billion, one hundred four million, two hundred twenty-one thousand, five hundred twenty-one".