21705368 has 16 divisors (see below), whose sum is σ = 41644680. Its totient is φ = 10600128.

The previous prime is 21705367. The next prime is 21705371. The reversal of 21705368 is 86350712.

It is a happy number.

It is a super-2 number, since 2×21705368² = 942246000030848, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21705367) by changing a digit.

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, 31205 + ... + 31892.

Almost surely, 2^21705368 is an apocalyptic number.

It is an amenable number.

21705368 is a deficient number, since it is larger than the sum of its proper divisors (19939312).

21705368 is a wasteful number, since it uses less digits than its factorization.

21705368 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63146 (or 63142 counting only the distinct ones).

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

The square root of 21705368 is about 4658.9020165700. The cubic root of 21705368 is about 278.9474428135.

The spelling of 21705368 in words is "twenty-one million, seven hundred five thousand, three hundred sixty-eight".