21336144 has 40 divisors (see below), whose sum is σ = 55323840. Its totient is φ = 7085568.

The previous prime is 21336137. The next prime is 21336151. The reversal of 21336144 is 44163312.

It is an interprime number because it is at equal distance from previous prime (21336137) and next prime (21336151).

It is a Harshad number since it is a multiple of its sum of digits (24).

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

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, 15517 + ... + 16835.

It is an arithmetic number, because the mean of its divisors is an integer number (1383096).

Almost surely, 2^21336144 is an apocalyptic number.

21336144 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21336144 is an abundant number, since it is smaller than the sum of its proper divisors (33987696).

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

21336144 is a wasteful number, since it uses less digits than its factorization.

21336144 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1667 (or 1661 counting only the distinct ones).

The product of its digits is 1728, while the sum is 24.

The square root of 21336144 is about 4619.1064070878. The cubic root of 21336144 is about 277.3566892518.

Adding to 21336144 its reverse (44163312), we get a palindrome (65499456).

The spelling of 21336144 in words is "twenty-one million, three hundred thirty-six thousand, one hundred forty-four".