21118249 has 2 divisors, whose sum is σ = 21118250. Its totient is φ = 21118248.

The previous prime is 21118247. The next prime is 21118277. The reversal of 21118249 is 94281112.

It is an a-pointer prime, because the next prime (21118277) can be obtained adding 21118249 to its sum of digits (28).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14707225 + 6411024 = 3835^2 + 2532^2 .

It is a cyclic number.

It is not a de Polignac number, because 21118249 - 2¹ = 21118247 is a prime.

Together with 21118247, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21118247) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10559124 + 10559125.

It is an arithmetic number, because the mean of its divisors is an integer number (10559125).

Almost surely, 2^21118249 is an apocalyptic number.

It is an amenable number.

21118249 is a deficient number, since it is larger than the sum of its proper divisors (1).

21118249 is an equidigital number, since it uses as much as digits as its factorization.

21118249 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1152, while the sum is 28.

The square root of 21118249 is about 4595.4596070469. The cubic root of 21118249 is about 276.4092900051.

The spelling of 21118249 in words is "twenty-one million, one hundred eighteen thousand, two hundred forty-nine".