21722271 has 12 divisors (see below), whose sum is σ = 29419992. Its totient is φ = 14256528.

The previous prime is 21722269. The next prime is 21722279. The reversal of 21722271 is 17222712.

It is not a de Polignac number, because 21722271 - 2¹ = 21722269 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21722279) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 12661 + ... + 14273.

It is an arithmetic number, because the mean of its divisors is an integer number (2451666).

Almost surely, 2^21722271 is an apocalyptic number.

21722271 is a deficient number, since it is larger than the sum of its proper divisors (7697721).

21722271 is an equidigital number, since it uses as much as digits as its factorization.

21722271 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1750 (or 1683 counting only the distinct ones).

The product of its digits is 784, while the sum is 24.

The square root of 21722271 is about 4660.7157175696. The cubic root of 21722271 is about 279.0198338953.

Adding to 21722271 its reverse (17222712), we get a palindrome (38944983).

The spelling of 21722271 in words is "twenty-one million, seven hundred twenty-two thousand, two hundred seventy-one".