42031921 has 2 divisors, whose sum is σ = 42031922. Its totient is φ = 42031920.

The previous prime is 42031919. The next prime is 42031937. The reversal of 42031921 is 12913024.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 32490000 + 9541921 = 5700^2 + 3089^2 .

It is a cyclic number.

It is not a de Polignac number, because 42031921 - 2¹ = 42031919 is a prime.

Together with 42031919, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 42031892 and 42031901.

It is not a weakly prime, because it can be changed into another prime (42031901) 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, 21015960 + 21015961.

It is an arithmetic number, because the mean of its divisors is an integer number (21015961).

Almost surely, 2^42031921 is an apocalyptic number.

It is an amenable number.

42031921 is a deficient number, since it is larger than the sum of its proper divisors (1).

42031921 is an equidigital number, since it uses as much as digits as its factorization.

42031921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 432, while the sum is 22.

The square root of 42031921 is about 6483.2029892639. The cubic root of 42031921 is about 347.6907042887.

Adding to 42031921 its reverse (12913024), we get a palindrome (54944945).

The spelling of 42031921 in words is "forty-two million, thirty-one thousand, nine hundred twenty-one".