21553344 has 56 divisors (see below), whose sum is σ = 63367920. Its totient is φ = 7183872.

The previous prime is 21553319. The next prime is 21553361. The reversal of 21553344 is 44335512.

It is a Harshad number since it is a multiple of its sum of digits (27).

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, 4509 + ... + 7964.

It is an arithmetic number, because the mean of its divisors is an integer number (1131570).

Almost surely, 2^21553344 is an apocalyptic number.

21553344 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21553344 is an abundant number, since it is smaller than the sum of its proper divisors (41814576).

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

21553344 is a wasteful number, since it uses less digits than its factorization.

21553344 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12494 (or 12478 counting only the distinct ones).

The product of its digits is 7200, while the sum is 27.

The square root of 21553344 is about 4642.5579156323. The cubic root of 21553344 is about 278.2946688337.

Adding to 21553344 its reverse (44335512), we get a palindrome (65888856).

The spelling of 21553344 in words is "twenty-one million, five hundred fifty-three thousand, three hundred forty-four".