21299203 has 4 divisors (see below), whose sum is σ = 21325968. Its totient is φ = 21272440.

The previous prime is 21299167. The next prime is 21299221. The reversal of 21299203 is 30299212.

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 21299203 - 2⁹ = 21298691 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21299273) 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, 12151 + ... + 13792.

It is an arithmetic number, because the mean of its divisors is an integer number (5331492).

Almost surely, 2^21299203 is an apocalyptic number.

21299203 is a deficient number, since it is larger than the sum of its proper divisors (26765).

21299203 is an equidigital number, since it uses as much as digits as its factorization.

21299203 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26764.

The product of its (nonzero) digits is 1944, while the sum is 28.

The square root of 21299203 is about 4615.1059576135. The cubic root of 21299203 is about 277.1965267235.

Subtracting 21299203 from its reverse (30299212), we obtain a palindrome (9000009).

The spelling of 21299203 in words is "twenty-one million, two hundred ninety-nine thousand, two hundred three".