21303231 has 32 divisors (see below), whose sum is σ = 31051776. Its totient is φ = 12960000.

The previous prime is 21303229. The next prime is 21303241. The reversal of 21303231 is 13230312.

It is not a de Polignac number, because 21303231 - 2¹ = 21303229 is a prime.

It is a super-2 number, since 2×21303231² = 907655302078722, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21303231.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21303241) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 141006 + ... + 141156.

It is an arithmetic number, because the mean of its divisors is an integer number (970368).

Almost surely, 2^21303231 is an apocalyptic number.

21303231 is a deficient number, since it is larger than the sum of its proper divisors (9748545).

21303231 is a wasteful number, since it uses less digits than its factorization.

21303231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 263.

The product of its (nonzero) digits is 108, while the sum is 15.

The square root of 21303231 is about 4615.5423299976. The cubic root of 21303231 is about 277.2139996344.

Adding to 21303231 its reverse (13230312), we get a palindrome (34533543).

The spelling of 21303231 in words is "twenty-one million, three hundred three thousand, two hundred thirty-one".