20216421 has 6 divisors (see below), whose sum is σ = 29201510. Its totient is φ = 13477608.

The previous prime is 20216411. The next prime is 20216447. The reversal of 20216421 is 12461202.

20216421 is a `hidden beast` number, since 2 + 0 + 21 + 642 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 14976900 + 5239521 = 3870^2 + 2289^2 .

It is not a de Polignac number, because 20216421 - 2¹¹ = 20214373 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20216394 and 20216403.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20216411) 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 5 ways as a sum of consecutive naturals, for example, 1123126 + ... + 1123143.

Almost surely, 2^20216421 is an apocalyptic number.

It is an amenable number.

20216421 is a deficient number, since it is larger than the sum of its proper divisors (8985089).

20216421 is a wasteful number, since it uses less digits than its factorization.

20216421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2246275 (or 2246272 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 20216421 is about 4496.2674520095. The cubic root of 20216421 is about 272.4173460850.

Adding to 20216421 its reverse (12461202), we get a palindrome (32677623).

The spelling of 20216421 in words is "twenty million, two hundred sixteen thousand, four hundred twenty-one".