21171249 has 18 divisors (see below), whose sum is σ = 33615218. Its totient is φ = 12830400.

The previous prime is 21171217. The next prime is 21171251. The reversal of 21171249 is 94217112.

It can be written as a sum of positive squares in only one way, i.e., 15681600 + 5489649 = 3960^2 + 2343^2 .

It is not a de Polignac number, because 21171249 - 2⁵ = 21171217 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21171049) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 8632 + ... + 10809.

Almost surely, 2^21171249 is an apocalyptic number.

It is an amenable number.

21171249 is a deficient number, since it is larger than the sum of its proper divisors (12443969).

21171249 is a wasteful number, since it uses less digits than its factorization.

21171249 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19469 (or 19455 counting only the distinct ones).

The product of its digits is 1008, while the sum is 27.

The square root of 21171249 is about 4601.2225549304. Note that the first 3 decimals coincide. The cubic root of 21171249 is about 276.6403295844.

The spelling of 21171249 in words is "twenty-one million, one hundred seventy-one thousand, two hundred forty-nine".