21338644 has 6 divisors (see below), whose sum is σ = 37342634. Its totient is φ = 10669320.

The previous prime is 21338627. The next prime is 21338651. The reversal of 21338644 is 44683312.

It can be written as a sum of positive squares in only one way, i.e., 14516100 + 6822544 = 3810^2 + 2612^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2667327 + ... + 2667334.

Almost surely, 2^21338644 is an apocalyptic number.

It is an amenable number.

21338644 is a deficient number, since it is larger than the sum of its proper divisors (16003990).

21338644 is a wasteful number, since it uses less digits than its factorization.

21338644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5334665 (or 5334663 counting only the distinct ones).

The product of its digits is 13824, while the sum is 31.

The square root of 21338644 is about 4619.3770142737. The cubic root of 21338644 is about 277.3675216471.

The spelling of 21338644 in words is "twenty-one million, three hundred thirty-eight thousand, six hundred forty-four".