21323231 has 4 divisors (see below), whose sum is σ = 22250352. Its totient is φ = 20396112.

The previous prime is 21323209. The next prime is 21323261. The reversal of 21323231 is 13232312.

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 21323231 - 2⁶ = 21323167 is a prime.

It is a super-2 number, since 2×21323231² = 909360360558722, which contains 22 as substring.

It is a Duffinian number.

It is a plaindrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21323261) 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, 463526 + ... + 463571.

It is an arithmetic number, because the mean of its divisors is an integer number (5562588).

Almost surely, 2^21323231 is an apocalyptic number.

21323231 is a deficient number, since it is larger than the sum of its proper divisors (927121).

21323231 is an equidigital number, since it uses as much as digits as its factorization.

21323231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 927120.

The product of its digits is 216, while the sum is 17.

The square root of 21323231 is about 4617.7084143545. The cubic root of 21323231 is about 277.3007242861.

Adding to 21323231 its reverse (13232312), we get a palindrome (34555543).

It can be divided in two parts, 2 and 1323231, that multiplied together give a palindrome (2646462).

The spelling of 21323231 in words is "twenty-one million, three hundred twenty-three thousand, two hundred thirty-one".