42530021 has 2 divisors, whose sum is σ = 42530022. Its totient is φ = 42530020.

The previous prime is 42530017. The next prime is 42530023. The reversal of 42530021 is 12003524.

42530021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 42393121 + 136900 = 6511^2 + 370^2 .

It is a cyclic number.

It is not a de Polignac number, because 42530021 - 2² = 42530017 is a prime.

It is a Sophie Germain prime.

Together with 42530023, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (42530023) 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, 21265010 + 21265011.

It is an arithmetic number, because the mean of its divisors is an integer number (21265011).

Almost surely, 2^42530021 is an apocalyptic number.

It is an amenable number.

42530021 is a deficient number, since it is larger than the sum of its proper divisors (1).

42530021 is an equidigital number, since it uses as much as digits as its factorization.

42530021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 240, while the sum is 17.

The square root of 42530021 is about 6521.5045043303. The cubic root of 42530021 is about 349.0587526257.

Adding to 42530021 its reverse (12003524), we get a palindrome (54533545).

The spelling of 42530021 in words is "forty-two million, five hundred thirty thousand, twenty-one".