21423203 has 4 divisors (see below), whose sum is σ = 22550760. Its totient is φ = 20295648.

The previous prime is 21423169. The next prime is 21423221. The reversal of 21423203 is 30232412.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21423203 - 2¹⁸ = 21161059 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21423223) 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, 563750 + ... + 563787.

It is an arithmetic number, because the mean of its divisors is an integer number (5637690).

Almost surely, 2^21423203 is an apocalyptic number.

21423203 is a deficient number, since it is larger than the sum of its proper divisors (1127557).

21423203 is a wasteful number, since it uses less digits than its factorization.

21423203 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1127556.

The product of its (nonzero) digits is 288, while the sum is 17.

The square root of 21423203 is about 4628.5206059820. The cubic root of 21423203 is about 277.7334150606.

Adding to 21423203 its reverse (30232412), we get a palindrome (51655615).

The spelling of 21423203 in words is "twenty-one million, four hundred twenty-three thousand, two hundred three".