21353171 has 6 divisors (see below), whose sum is σ = 24839460. Its totient is φ = 18302676.

The previous prime is 21353159. The next prime is 21353191. The reversal of 21353171 is 17135312.

It is not a de Polignac number, because 21353171 - 2¹⁴ = 21336787 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21353191) 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 5 ways as a sum of consecutive naturals, for example, 217841 + ... + 217938.

It is an arithmetic number, because the mean of its divisors is an integer number (4139910).

Almost surely, 2^21353171 is an apocalyptic number.

21353171 is a deficient number, since it is larger than the sum of its proper divisors (3486289).

21353171 is an equidigital number, since it uses as much as digits as its factorization.

21353171 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 435793 (or 435786 counting only the distinct ones).

The product of its digits is 630, while the sum is 23.

The square root of 21353171 is about 4620.9491449268. The cubic root of 21353171 is about 277.4304497940.

Adding to 21353171 its reverse (17135312), we get a palindrome (38488483).

The spelling of 21353171 in words is "twenty-one million, three hundred fifty-three thousand, one hundred seventy-one".