21709544 has 16 divisors (see below), whose sum is σ = 43100100. Its totient is φ = 10216192.

The previous prime is 21709531. The next prime is 21709553. The reversal of 21709544 is 44590712.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 17556100 + 4153444 = 4190^2 + 2038^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21709544.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 79679 + ... + 79950.

Almost surely, 2^21709544 is an apocalyptic number.

It is an amenable number.

21709544 is a deficient number, since it is larger than the sum of its proper divisors (21390556).

21709544 is a wasteful number, since it uses less digits than its factorization.

21709544 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 159652 (or 159648 counting only the distinct ones).

The product of its (nonzero) digits is 10080, while the sum is 32.

The square root of 21709544 is about 4659.3501692833. The cubic root of 21709544 is about 278.9653310124.

The spelling of 21709544 in words is "twenty-one million, seven hundred nine thousand, five hundred forty-four".