20421202421 has 8 divisors (see below), whose sum is σ = 20556801720. Its totient is φ = 20285673408.

The previous prime is 20421202391. The next prime is 20421202447. The reversal of 20421202421 is 12420212402.

It can be written as a sum of positive squares in 4 ways, for example, as 6607901521 + 13813300900 = 81289^2 + 117530^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20421202421 is a prime.

It is a super-2 number, since 2×20421202421² (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 = 20421202393 and 20421202402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20421202481) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 648575 + ... + 679331.

It is an arithmetic number, because the mean of its divisors is an integer number (2569600215).

Almost surely, 2^20421202421 is an apocalyptic number.

It is an amenable number.

20421202421 is a deficient number, since it is larger than the sum of its proper divisors (135599299).

20421202421 is a wasteful number, since it uses less digits than its factorization.

20421202421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35143.

The product of its (nonzero) digits is 512, while the sum is 20.

Adding to 20421202421 its reverse (12420212402), we get a palindrome (32841414823).

The spelling of 20421202421 in words is "twenty billion, four hundred twenty-one million, two hundred two thousand, four hundred twenty-one".