20421427 has 4 divisors (see below), whose sum is σ = 21992320. Its totient is φ = 18850536.

The previous prime is 20421419. The next prime is 20421433. The reversal of 20421427 is 72412402.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 72412402 = 2 ⋅36206201.

It is a cyclic number.

It is not a de Polignac number, because 20421427 - 2³ = 20421419 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20421398 and 20421407.

It is not an unprimeable number, because it can be changed into a prime (20421407) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 785427 + ... + 785452.

It is an arithmetic number, because the mean of its divisors is an integer number (5498080).

Almost surely, 2^20421427 is an apocalyptic number.

20421427 is a deficient number, since it is larger than the sum of its proper divisors (1570893).

20421427 is a wasteful number, since it uses less digits than its factorization.

20421427 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1570892.

The product of its (nonzero) digits is 896, while the sum is 22.

The square root of 20421427 is about 4519.0073024947. The cubic root of 20421427 is about 273.3350731927.

Adding to 20421427 its reverse (72412402), we get a palindrome (92833829).

The spelling of 20421427 in words is "twenty million, four hundred twenty-one thousand, four hundred twenty-seven".