21039544 has 8 divisors (see below), whose sum is σ = 39449160. Its totient is φ = 10519768.

The previous prime is 21039527. The next prime is 21039559. The reversal of 21039544 is 44593012.

It is a tau number, because it is divible by the number of its divisors (8).

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, 1314964 + ... + 1314979.

It is an arithmetic number, because the mean of its divisors is an integer number (4931145).

Almost surely, 2^21039544 is an apocalyptic number.

It is an amenable number.

21039544 is a deficient number, since it is larger than the sum of its proper divisors (18409616).

21039544 is a wasteful number, since it uses less digits than its factorization.

21039544 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2629949 (or 2629945 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 21039544 is about 4586.8882698405. Note that the first 3 decimals coincide. The cubic root of 21039544 is about 276.0654819075.

The spelling of 21039544 in words is "twenty-one million, thirty-nine thousand, five hundred forty-four".