21120243421 has 16 divisors (see below), whose sum is σ = 22670144640. Its totient is φ = 19618027200.

The previous prime is 21120243283. The next prime is 21120243461. The reversal of 21120243421 is 12434202112.

It is a cyclic number.

It is not a de Polignac number, because 21120243421 - 2²⁵ = 21086688989 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21120243392 and 21120243401.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21120243461) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 144231 + ... + 251083.

It is an arithmetic number, because the mean of its divisors is an integer number (1416884040).

Almost surely, 2^21120243421 is an apocalyptic number.

It is an amenable number.

21120243421 is a deficient number, since it is larger than the sum of its proper divisors (1549901219).

21120243421 is a wasteful number, since it uses less digits than its factorization.

21120243421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 107076.

The product of its (nonzero) digits is 768, while the sum is 22.

Adding to 21120243421 its reverse (12434202112), we get a palindrome (33554445533).

The spelling of 21120243421 in words is "twenty-one billion, one hundred twenty million, two hundred forty-three thousand, four hundred twenty-one".