20421124321 has 4 divisors (see below), whose sum is σ = 21991980052. Its totient is φ = 18850268592.

The previous prime is 20421124307. The next prime is 20421124331. The reversal of 20421124321 is 12342112402.

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 3170928721 + 17250195600 = 56311^2 + 131340^2 .

It is a cyclic number.

It is not a de Polignac number, because 20421124321 - 2⁵ = 20421124289 is a prime.

It is a super-2 number, since 2×20421124321² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20421124292 and 20421124301.

It is not an unprimeable number, because it can be changed into a prime (20421124331) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 785427846 + ... + 785427871.

It is an arithmetic number, because the mean of its divisors is an integer number (5497995013).

Almost surely, 2^20421124321 is an apocalyptic number.

It is an amenable number.

20421124321 is a deficient number, since it is larger than the sum of its proper divisors (1570855731).

20421124321 is a wasteful number, since it uses less digits than its factorization.

20421124321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1570855730.

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

Adding to 20421124321 its reverse (12342112402), we get a palindrome (32763236723).

The spelling of 20421124321 in words is "twenty billion, four hundred twenty-one million, one hundred twenty-four thousand, three hundred twenty-one".