21075239 has 2 divisors, whose sum is σ = 21075240. Its totient is φ = 21075238.

The previous prime is 21075227. The next prime is 21075247. The reversal of 21075239 is 93257012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21075239 - 2²⁴ = 4298023 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21075839) 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, 10537619 + 10537620.

It is an arithmetic number, because the mean of its divisors is an integer number (10537620).

Almost surely, 2^21075239 is an apocalyptic number.

21075239 is a deficient number, since it is larger than the sum of its proper divisors (1).

21075239 is an equidigital number, since it uses as much as digits as its factorization.

21075239 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3780, while the sum is 29.

The square root of 21075239 is about 4590.7776029775. Note that the first 3 decimals coincide. The cubic root of 21075239 is about 276.2215149133.

The spelling of 21075239 in words is "twenty-one million, seventy-five thousand, two hundred thirty-nine".