21398203 has 4 divisors (see below), whose sum is σ = 21413200. Its totient is φ = 21383208.

The previous prime is 21398191. The next prime is 21398227. The reversal of 21398203 is 30289312.

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

It is a cyclic number.

It is not a de Polignac number, because 21398203 - 2⁵ = 21398171 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21398233) 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, 5103 + ... + 8296.

It is an arithmetic number, because the mean of its divisors is an integer number (5353300).

Almost surely, 2^21398203 is an apocalyptic number.

21398203 is a deficient number, since it is larger than the sum of its proper divisors (14997).

21398203 is a wasteful number, since it uses less digits than its factorization.

21398203 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14996.

The product of its (nonzero) digits is 2592, while the sum is 28.

The square root of 21398203 is about 4625.8191706983. The cubic root of 21398203 is about 277.6253385047.

Subtracting from 21398203 its product of nonzero digits (2592), we obtain a triangular number (21395611 = T₆₅₄₁).

The spelling of 21398203 in words is "twenty-one million, three hundred ninety-eight thousand, two hundred three".