21144231 has 12 divisors (see below), whose sum is σ = 30961008. Its totient is φ = 13902624.

The previous prime is 21144229. The next prime is 21144259. The reversal of 21144231 is 13244112.

It is not a de Polignac number, because 21144231 - 2¹ = 21144229 is a prime.

It is a super-2 number, since 2×21144231² = 894157009162722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21144631) 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 11 ways as a sum of consecutive naturals, for example, 15435 + ... + 16748.

It is an arithmetic number, because the mean of its divisors is an integer number (2580084).

Almost surely, 2^21144231 is an apocalyptic number.

21144231 is a deficient number, since it is larger than the sum of its proper divisors (9816777).

21144231 is a wasteful number, since it uses less digits than its factorization.

21144231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32262 (or 32259 counting only the distinct ones).

The product of its digits is 192, while the sum is 18.

The square root of 21144231 is about 4598.2856588081. The cubic root of 21144231 is about 276.5225999510.

Adding to 21144231 its reverse (13244112), we get a palindrome (34388343).

The spelling of 21144231 in words is "twenty-one million, one hundred forty-four thousand, two hundred thirty-one".