21345231 has 8 divisors (see below), whose sum is σ = 28487680. Its totient is φ = 14216472.

The previous prime is 21345229. The next prime is 21345241. The reversal of 21345231 is 13254312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21345231 - 2¹ = 21345229 is a prime.

It is a super-2 number, since 2×21345231² = 911237772886722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21345198 and 21345207.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21345211) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1056 + ... + 6618.

It is an arithmetic number, because the mean of its divisors is an integer number (3560960).

Almost surely, 2^21345231 is an apocalyptic number.

21345231 is a deficient number, since it is larger than the sum of its proper divisors (7142449).

21345231 is a wasteful number, since it uses less digits than its factorization.

21345231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6845.

The product of its digits is 720, while the sum is 21.

The square root of 21345231 is about 4620.0899341896. The cubic root of 21345231 is about 277.3960587917.

Adding to 21345231 its reverse (13254312), we get a palindrome (34599543).

The spelling of 21345231 in words is "twenty-one million, three hundred forty-five thousand, two hundred thirty-one".