21644612 has 12 divisors (see below), whose sum is σ = 41321616. Its totient is φ = 9838440.

The previous prime is 21644611. The next prime is 21644627.

21644612 is nontrivially palindromic in base 10.

It is not an unprimeable number, because it can be changed into a prime (21644611) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 245918 + ... + 246005.

It is an arithmetic number, because the mean of its divisors is an integer number (3443468).

Almost surely, 2^21644612 is an apocalyptic number.

21644612 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

21644612 is a deficient number, since it is larger than the sum of its proper divisors (19677004).

21644612 is a wasteful number, since it uses less digits than its factorization.

21644612 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 491938 (or 491936 counting only the distinct ones).

The product of its digits is 2304, while the sum is 26.

The square root of 21644612 is about 4652.3770268541. The cubic root of 21644612 is about 278.6869301698.

It can be divided in two parts, 2164 and 4612, that added together give a palindrome (6776).

The spelling of 21644612 in words is "twenty-one million, six hundred forty-four thousand, six hundred twelve".