21045144 has 32 divisors (see below), whose sum is σ = 52899840. Its totient is φ = 6976800.

The previous prime is 21045139. The next prime is 21045149. The reversal of 21045144 is 44154012.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21045139) and next prime (21045149).

It is a self number, because there is not a number n which added to its sum of digits gives 21045144.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21045149) 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, 2289 + ... + 6879.

It is an arithmetic number, because the mean of its divisors is an integer number (1653120).

Almost surely, 2^21045144 is an apocalyptic number.

21045144 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21045144 is an abundant number, since it is smaller than the sum of its proper divisors (31854696).

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

21045144 is a wasteful number, since it uses less digits than its factorization.

21045144 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4791 (or 4787 counting only the distinct ones).

The product of its (nonzero) digits is 640, while the sum is 21.

The square root of 21045144 is about 4587.4986648499. The cubic root of 21045144 is about 276.0899727671.

Adding to 21045144 its reverse (44154012), we get a palindrome (65199156).

It can be divided in two parts, 210 and 45144, that added together give a palindrome (45354).

The spelling of 21045144 in words is "twenty-one million, forty-five thousand, one hundred forty-four".