21103231 has 4 divisors (see below), whose sum is σ = 21210552. Its totient is φ = 20995912.

The previous prime is 21103217. The next prime is 21103241. The reversal of 21103231 is 13230112.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21103231 is a prime.

It is a super-2 number, since 2×21103231² = 890692717278722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21103211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 53365 + ... + 53758.

It is an arithmetic number, because the mean of its divisors is an integer number (5302638).

Almost surely, 2^21103231 is an apocalyptic number.

21103231 is a deficient number, since it is larger than the sum of its proper divisors (107321).

21103231 is a wasteful number, since it uses less digits than its factorization.

21103231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 107320.

The product of its (nonzero) digits is 36, while the sum is 13.

The square root of 21103231 is about 4593.8253123078. The cubic root of 21103231 is about 276.3437527043.

Adding to 21103231 its reverse (13230112), we get a palindrome (34333343).

The spelling of 21103231 in words is "twenty-one million, one hundred three thousand, two hundred thirty-one".