20421173 has 4 divisors (see below), whose sum is σ = 20896128. Its totient is φ = 19946220.

The previous prime is 20421103. The next prime is 20421179. The reversal of 20421173 is 37112402.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20421173 - 2¹⁶ = 20355637 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20421179) 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, 237413 + ... + 237498.

It is an arithmetic number, because the mean of its divisors is an integer number (5224032).

Almost surely, 2^20421173 is an apocalyptic number.

It is an amenable number.

20421173 is a deficient number, since it is larger than the sum of its proper divisors (474955).

20421173 is an equidigital number, since it uses as much as digits as its factorization.

20421173 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 474954.

The product of its (nonzero) digits is 336, while the sum is 20.

The square root of 20421173 is about 4518.9791988899. The cubic root of 20421173 is about 273.3339399484. Note that the first 3 decimals are identical.

Adding to 20421173 its reverse (37112402), we get a palindrome (57533575).

It can be divided in two parts, 20 and 421173, that multiplied together give a triangular number (8423460 = T₄₁₀₄).

The spelling of 20421173 in words is "twenty million, four hundred twenty-one thousand, one hundred seventy-three".