21242231 has 8 divisors (see below), whose sum is σ = 22777920. Its totient is φ = 19738368.

The previous prime is 21242203. The next prime is 21242237. The reversal of 21242231 is 13224212.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21242231 is a prime.

It is a super-2 number, since 2×21242231² = 902464755714722, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (17).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21242237) 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 7 ways as a sum of consecutive naturals, for example, 6566 + ... + 9251.

It is an arithmetic number, because the mean of its divisors is an integer number (2847240).

Almost surely, 2^21242231 is an apocalyptic number.

21242231 is a deficient number, since it is larger than the sum of its proper divisors (1535689).

21242231 is a wasteful number, since it uses less digits than its factorization.

21242231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15913.

The product of its digits is 192, while the sum is 17.

The square root of 21242231 is about 4608.9294852493. The cubic root of 21242231 is about 276.9491537390.

Adding to 21242231 its reverse (13224212), we get a palindrome (34466443).

The spelling of 21242231 in words is "twenty-one million, two hundred forty-two thousand, two hundred thirty-one".