21423544 has 16 divisors (see below), whose sum is σ = 40374000. Its totient is φ = 10657152.

The previous prime is 21423539. The next prime is 21423559. The reversal of 21423544 is 44532412.

It is a happy number.

It is a super-3 number, since 3×21423544³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5137 + ... + 8320.

It is an arithmetic number, because the mean of its divisors is an integer number (2523375).

Almost surely, 2^21423544 is an apocalyptic number.

It is an amenable number.

21423544 is a deficient number, since it is larger than the sum of its proper divisors (18950456).

21423544 is a wasteful number, since it uses less digits than its factorization.

21423544 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13662 (or 13658 counting only the distinct ones).

The product of its digits is 3840, while the sum is 25.

The square root of 21423544 is about 4628.5574426596. The cubic root of 21423544 is about 277.7348886434.

Adding to 21423544 its reverse (44532412), we get a palindrome (65955956).

The spelling of 21423544 in words is "twenty-one million, four hundred twenty-three thousand, five hundred forty-four".