21685339 has 8 divisors (see below), whose sum is σ = 23390640. Its totient is φ = 19985376.

The previous prime is 21685333. The next prime is 21685361. The reversal of 21685339 is 93358612.

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

It is a cyclic number.

It is not a de Polignac number, because 21685339 - 2⁷ = 21685211 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21685298 and 21685307.

It is not an unprimeable number, because it can be changed into a prime (21685333) by changing a digit.

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 in 7 ways as a sum of consecutive naturals, for example, 12429 + ... + 14065.

It is an arithmetic number, because the mean of its divisors is an integer number (2923830).

Almost surely, 2^21685339 is an apocalyptic number.

21685339 is a deficient number, since it is larger than the sum of its proper divisors (1705301).

21685339 is a wasteful number, since it uses less digits than its factorization.

21685339 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2669.

The product of its digits is 38880, while the sum is 37.

The square root of 21685339 is about 4656.7519796528. The cubic root of 21685339 is about 278.8616152320.

The spelling of 21685339 in words is "twenty-one million, six hundred eighty-five thousand, three hundred thirty-nine".