21144144 has 40 divisors (see below), whose sum is σ = 62426560. Its totient is φ = 6041088.

The previous prime is 21144121. The next prime is 21144173. The reversal of 21144144 is 44144112.

It is a Harshad number since it is a multiple of its sum of digits (21).

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 21144144.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 31129 + ... + 31800.

It is an arithmetic number, because the mean of its divisors is an integer number (1560664).

Almost surely, 2^21144144 is an apocalyptic number.

21144144 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21144144 is an abundant number, since it is smaller than the sum of its proper divisors (41282416).

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

21144144 is a wasteful number, since it uses less digits than its factorization.

21144144 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 62947 (or 62941 counting only the distinct ones).

The product of its digits is 512, while the sum is 21.

The square root of 21144144 is about 4598.2761987510. The cubic root of 21144144 is about 276.5222206908.

Adding to 21144144 its reverse (44144112), we get a palindrome (65288256).

The spelling of 21144144 in words is "twenty-one million, one hundred forty-four thousand, one hundred forty-four".