21443644 has 12 divisors (see below), whose sum is σ = 38820600. Its totient is φ = 10352048.

The previous prime is 21443629. The next prime is 21443657. The reversal of 21443644 is 44634412.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 92314 + ... + 92545.

It is an arithmetic number, because the mean of its divisors is an integer number (3235050).

Almost surely, 2^21443644 is an apocalyptic number.

It is an amenable number.

21443644 is a deficient number, since it is larger than the sum of its proper divisors (17376956).

21443644 is a wasteful number, since it uses less digits than its factorization.

21443644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 184892 (or 184890 counting only the distinct ones).

The product of its digits is 9216, while the sum is 28.

The square root of 21443644 is about 4630.7282364656. The cubic root of 21443644 is about 277.8217203134.

The spelling of 21443644 in words is "twenty-one million, four hundred forty-three thousand, six hundred forty-four".