21544516 has 48 divisors (see below), whose sum is σ = 45158400. Its totient is φ = 8984640.

The previous prime is 21544513. The next prime is 21544517. The reversal of 21544516 is 61544512.

It is a hoax number, since the sum of its digits (28) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21544513) 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 15 ways as a sum of consecutive naturals, for example, 56061 + ... + 56443.

It is an arithmetic number, because the mean of its divisors is an integer number (940800).

Almost surely, 2^21544516 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21544516, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22579200).

21544516 is an abundant number, since it is smaller than the sum of its proper divisors (23613884).

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

21544516 is a wasteful number, since it uses less digits than its factorization.

21544516 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 449 (or 433 counting only the distinct ones).

The product of its digits is 4800, while the sum is 28.

The square root of 21544516 is about 4641.6070492880. The cubic root of 21544516 is about 278.2566682209.

It can be divided in two parts, 2154 and 4516, that added together give a triangular number (6670 = T₁₁₅).

The spelling of 21544516 in words is "twenty-one million, five hundred forty-four thousand, five hundred sixteen".