21071249 has 2 divisors, whose sum is σ = 21071250. Its totient is φ = 21071248.

The previous prime is 21071221. The next prime is 21071251. The reversal of 21071249 is 94217012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11950849 + 9120400 = 3457^2 + 3020^2 .

It is a cyclic number.

It is not a de Polignac number, because 21071249 - 2¹⁶ = 21005713 is a prime.

Together with 21071251, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21071549) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10535624 + 10535625.

It is an arithmetic number, because the mean of its divisors is an integer number (10535625).

Almost surely, 2^21071249 is an apocalyptic number.

It is an amenable number.

21071249 is a deficient number, since it is larger than the sum of its proper divisors (1).

21071249 is an equidigital number, since it uses as much as digits as its factorization.

21071249 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1008, while the sum is 26.

The square root of 21071249 is about 4590.3430155055. The cubic root of 21071249 is about 276.2040822379.

The spelling of 21071249 in words is "twenty-one million, seventy-one thousand, two hundred forty-nine".