21708271 has 8 divisors (see below), whose sum is σ = 23418080. Its totient is φ = 20004192.

The previous prime is 21708263. The next prime is 21708287. The reversal of 21708271 is 17280712.

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

It is not a de Polignac number, because 21708271 - 2³ = 21708263 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21708221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9685 + ... + 11713.

It is an arithmetic number, because the mean of its divisors is an integer number (2927260).

Almost surely, 2^21708271 is an apocalyptic number.

21708271 is a deficient number, since it is larger than the sum of its proper divisors (1709809).

21708271 is a wasteful number, since it uses less digits than its factorization.

21708271 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2865.

The product of its (nonzero) digits is 1568, while the sum is 28.

The square root of 21708271 is about 4659.2135602481. The cubic root of 21708271 is about 278.9598782677.

Adding to 21708271 its reverse (17280712), we get a palindrome (38988983).

The spelling of 21708271 in words is "twenty-one million, seven hundred eight thousand, two hundred seventy-one".