21643118 has 16 divisors (see below), whose sum is σ = 37243104. Its totient is φ = 9240480.

The previous prime is 21643117. The next prime is 21643129. The reversal of 21643118 is 81134612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21643117) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1088 + ... + 6668.

It is an arithmetic number, because the mean of its divisors is an integer number (2327694).

Almost surely, 2^21643118 is an apocalyptic number.

21643118 is a deficient number, since it is larger than the sum of its proper divisors (15599986).

21643118 is a wasteful number, since it uses less digits than its factorization.

21643118 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5867.

The product of its digits is 1152, while the sum is 26.

The square root of 21643118 is about 4652.2164610001. The cubic root of 21643118 is about 278.6805179835.

It can be divided in two parts, 216 and 43118, that added together give a palindrome (43334).

The spelling of 21643118 in words is "twenty-one million, six hundred forty-three thousand, one hundred eighteen".