42945809 has 2 divisors, whose sum is σ = 42945810. Its totient is φ = 42945808.

The previous prime is 42945797. The next prime is 42945811. The reversal of 42945809 is 90854924.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 35438209 + 7507600 = 5953^2 + 2740^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-42945809 is a prime.

Together with 42945811, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (42945829) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21472904 + 21472905.

It is an arithmetic number, because the mean of its divisors is an integer number (21472905).

Almost surely, 2^42945809 is an apocalyptic number.

It is an amenable number.

42945809 is a deficient number, since it is larger than the sum of its proper divisors (1).

42945809 is an equidigital number, since it uses as much as digits as its factorization.

42945809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 103680, while the sum is 41.

The square root of 42945809 is about 6553.3051966164. The cubic root of 42945809 is about 350.1925715778.

The spelling of 42945809 in words is "forty-two million, nine hundred forty-five thousand, eight hundred nine".