21239203 has 2 divisors, whose sum is σ = 21239204. Its totient is φ = 21239202.

The previous prime is 21239191. The next prime is 21239237. The reversal of 21239203 is 30293212.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21239203 is a prime.

It is a super-2 number, since 2×21239203² = 902207488150418, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21239243) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10619601 + 10619602.

It is an arithmetic number, because the mean of its divisors is an integer number (10619602).

Almost surely, 2^21239203 is an apocalyptic number.

21239203 is a deficient number, since it is larger than the sum of its proper divisors (1).

21239203 is an equidigital number, since it uses as much as digits as its factorization.

21239203 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 648, while the sum is 22.

The square root of 21239203 is about 4608.6009807750. The cubic root of 21239203 is about 276.9359937608.

The spelling of 21239203 in words is "twenty-one million, two hundred thirty-nine thousand, two hundred three".