21143251 has 2 divisors, whose sum is σ = 21143252. Its totient is φ = 21143250.

The previous prime is 21143207. The next prime is 21143261. The reversal of 21143251 is 15234112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21143251 - 2¹⁹ = 20618963 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21143201) 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 as a sum of consecutive naturals, namely, 10571625 + 10571626.

It is an arithmetic number, because the mean of its divisors is an integer number (10571626).

Almost surely, 2^21143251 is an apocalyptic number.

21143251 is a deficient number, since it is larger than the sum of its proper divisors (1).

21143251 is an equidigital number, since it uses as much as digits as its factorization.

21143251 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 240, while the sum is 19.

The square root of 21143251 is about 4598.1790961206. The cubic root of 21143251 is about 276.5183277639.

Adding to 21143251 its reverse (15234112), we get a palindrome (36377363).

The spelling of 21143251 in words is "twenty-one million, one hundred forty-three thousand, two hundred fifty-one".