21271249 has 4 divisors (see below), whose sum is σ = 21620020. Its totient is φ = 20922480.

The previous prime is 21271247. The next prime is 21271253. The reversal of 21271249 is 94217212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1849600 + 19421649 = 1360^2 + 4407^2 .

It is a cyclic number.

It is not a de Polignac number, because 21271249 - 2¹ = 21271247 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21271247) 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, 174294 + ... + 174415.

It is an arithmetic number, because the mean of its divisors is an integer number (5405005).

Almost surely, 2^21271249 is an apocalyptic number.

It is an amenable number.

21271249 is a deficient number, since it is larger than the sum of its proper divisors (348771).

21271249 is an equidigital number, since it uses as much as digits as its factorization.

21271249 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 348770.

The product of its digits is 2016, while the sum is 28.

The square root of 21271249 is about 4612.0764304161. The cubic root of 21271249 is about 277.0752053746.

The spelling of 21271249 in words is "twenty-one million, two hundred seventy-one thousand, two hundred forty-nine".