21243144 has 32 divisors (see below), whose sum is σ = 57193920. Its totient is φ = 6536256.

The previous prime is 21243139. The next prime is 21243151. The reversal of 21243144 is 44134212.

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 21243144.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 33732 + ... + 34355.

It is an arithmetic number, because the mean of its divisors is an integer number (1787310).

Almost surely, 2^21243144 is an apocalyptic number.

21243144 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21243144 is an abundant number, since it is smaller than the sum of its proper divisors (35950776).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21243144 is a wasteful number, since it uses less digits than its factorization.

21243144 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 68109 (or 68105 counting only the distinct ones).

The product of its digits is 768, while the sum is 21.

The square root of 21243144 is about 4609.0285310464. The cubic root of 21243144 is about 276.9531214791.

Adding to 21243144 its reverse (44134212), we get a palindrome (65377356).

The spelling of 21243144 in words is "twenty-one million, two hundred forty-three thousand, one hundred forty-four".