20421245421 has 12 divisors (see below), whose sum is σ = 30589849472. Its totient is φ = 13614163452.

The previous prime is 20421245417. The next prime is 20421245447. The reversal of 20421245421 is 12454212402.

It is a happy number.

20421245421 is a `hidden beast` number, since 20 + 4 + 212 + 4 + 5 + 421 = 666.

It is not a de Polignac number, because 20421245421 - 2² = 20421245417 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20421247421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 42018781 + ... + 42019266.

Almost surely, 2^20421245421 is an apocalyptic number.

It is an amenable number.

20421245421 is a deficient number, since it is larger than the sum of its proper divisors (10168604051).

20421245421 is an frugal number, since it uses more digits than its factorization.

20421245421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 84038062 (or 84038050 counting only the distinct ones).

The product of its (nonzero) digits is 5120, while the sum is 27.

Adding to 20421245421 its reverse (12454212402), we get a palindrome (32875457823).

The spelling of 20421245421 in words is "twenty billion, four hundred twenty-one million, two hundred forty-five thousand, four hundred twenty-one".