21715271 has 4 divisors (see below), whose sum is σ = 22858200. Its totient is φ = 20572344.

The previous prime is 21715259. The next prime is 21715277. The reversal of 21715271 is 17251712.

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 21715271 - 2¹⁰ = 21714247 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21715271.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21715277) 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 3 ways as a sum of consecutive naturals, for example, 571436 + ... + 571473.

It is an arithmetic number, because the mean of its divisors is an integer number (5714550).

Almost surely, 2^21715271 is an apocalyptic number.

21715271 is a deficient number, since it is larger than the sum of its proper divisors (1142929).

21715271 is a wasteful number, since it uses less digits than its factorization.

21715271 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1142928.

The product of its digits is 980, while the sum is 26.

The square root of 21715271 is about 4659.9646994371. The cubic root of 21715271 is about 278.9898593026.

Adding to 21715271 its reverse (17251712), we get a palindrome (38966983).

The spelling of 21715271 in words is "twenty-one million, seven hundred fifteen thousand, two hundred seventy-one".