21713271 has 4 divisors (see below), whose sum is σ = 28951032. Its totient is φ = 14475512.

The previous prime is 21713261. The next prime is 21713273. The reversal of 21713271 is 17231712.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21713271 - 2⁶ = 21713207 is a prime.

It is a super-2 number, since 2×21713271² = 942932275038882, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21713273) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3618876 + ... + 3618881.

It is an arithmetic number, because the mean of its divisors is an integer number (7237758).

Almost surely, 2^21713271 is an apocalyptic number.

21713271 is a deficient number, since it is larger than the sum of its proper divisors (7237761).

21713271 is an equidigital number, since it uses as much as digits as its factorization.

21713271 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7237760.

The product of its digits is 588, while the sum is 24.

The square root of 21713271 is about 4659.7501005955. The cubic root of 21713271 is about 278.9812939502.

Adding to 21713271 its reverse (17231712), we get a palindrome (38944983).

The spelling of 21713271 in words is "twenty-one million, seven hundred thirteen thousand, two hundred seventy-one".