21768144 has 40 divisors (see below), whose sum is σ = 57436800. Its totient is φ = 7100928.

The previous prime is 21768133. The next prime is 21768179. The reversal of 21768144 is 44186712.

It is a congruent number.

It is an unprimeable number.

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, 2569 + ... + 7080.

It is an arithmetic number, because the mean of its divisors is an integer number (1435920).

Almost surely, 2^21768144 is an apocalyptic number.

21768144 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21768144 is an abundant number, since it is smaller than the sum of its proper divisors (35668656).

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

21768144 is a wasteful number, since it uses less digits than its factorization.

21768144 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9707 (or 9701 counting only the distinct ones).

The product of its digits is 10752, while the sum is 33.

The square root of 21768144 is about 4665.6343620134. The cubic root of 21768144 is about 279.2161067656.

It can be divided in two parts, 21768 and 144, that added together give a palindrome (21912).

The spelling of 21768144 in words is "twenty-one million, seven hundred sixty-eight thousand, one hundred forty-four".