42240409 has 2 divisors, whose sum is σ = 42240410. Its totient is φ = 42240408.

The previous prime is 42240391. The next prime is 42240413. The reversal of 42240409 is 90404224.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 39690000 + 2550409 = 6300^2 + 1597^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-42240409 is a prime.

It is not a weakly prime, because it can be changed into another prime (42240469) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21120204 + 21120205.

It is an arithmetic number, because the mean of its divisors is an integer number (21120205).

Almost surely, 2^42240409 is an apocalyptic number.

It is an amenable number.

42240409 is a deficient number, since it is larger than the sum of its proper divisors (1).

42240409 is an equidigital number, since it uses as much as digits as its factorization.

42240409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2304, while the sum is 25.

The square root of 42240409 is about 6499.2621888950. The cubic root of 42240409 is about 348.2646316946.

The spelling of 42240409 in words is "forty-two million, two hundred forty thousand, four hundred nine".