21717944 has 8 divisors (see below), whose sum is σ = 40721160. Its totient is φ = 10858968.

The previous prime is 21717937. The next prime is 21717953. The reversal of 21717944 is 44971712.

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 pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1357364 + ... + 1357379.

It is an arithmetic number, because the mean of its divisors is an integer number (5090145).

Almost surely, 2^21717944 is an apocalyptic number.

It is an amenable number.

21717944 is a deficient number, since it is larger than the sum of its proper divisors (19003216).

21717944 is a wasteful number, since it uses less digits than its factorization.

21717944 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2714749 (or 2714745 counting only the distinct ones).

The product of its digits is 14112, while the sum is 35.

The square root of 21717944 is about 4660.2514953595. The cubic root of 21717944 is about 279.0013060751.

The spelling of 21717944 in words is "twenty-one million, seven hundred seventeen thousand, nine hundred forty-four".