21422171 has 4 divisors (see below), whose sum is σ = 21432912. Its totient is φ = 21411432.

The previous prime is 21422143. The next prime is 21422221. The reversal of 21422171 is 17122412.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21422171 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21424171) 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, 1400 + ... + 6693.

It is an arithmetic number, because the mean of its divisors is an integer number (5358228).

Almost surely, 2^21422171 is an apocalyptic number.

21422171 is a deficient number, since it is larger than the sum of its proper divisors (10741).

21422171 is an equidigital number, since it uses as much as digits as its factorization.

21422171 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10740.

The product of its digits is 224, while the sum is 20.

The square root of 21422171 is about 4628.4091219338. The cubic root of 21422171 is about 277.7289553246.

Adding to 21422171 its reverse (17122412), we get a palindrome (38544583).

The spelling of 21422171 in words is "twenty-one million, four hundred twenty-two thousand, one hundred seventy-one".