21688683 has 8 divisors (see below), whose sum is σ = 28942848. Its totient is φ = 14446824.

The previous prime is 21688669. The next prime is 21688699. The reversal of 21688683 is 38688612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21688683 - 2⁶ = 21688619 is a prime.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (21688603) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2466 + ... + 7032.

It is an arithmetic number, because the mean of its divisors is an integer number (3617856).

Almost surely, 2^21688683 is an apocalyptic number.

21688683 is a deficient number, since it is larger than the sum of its proper divisors (7254165).

21688683 is a wasteful number, since it uses less digits than its factorization.

21688683 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6153.

The product of its digits is 110592, while the sum is 42.

The square root of 21688683 is about 4657.1110143521. Note that the first 3 decimals coincide. The cubic root of 21688683 is about 278.8759484997.

The spelling of 21688683 in words is "twenty-one million, six hundred eighty-eight thousand, six hundred eighty-three".