42878209 has 4 divisors (see below), whose sum is σ = 46776240. Its totient is φ = 38980180.

The previous prime is 42878201. The next prime is 42878261. The reversal of 42878209 is 90287824.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 42878209 - 2³ = 42878201 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (42878201) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1948999 + ... + 1949020.

It is an arithmetic number, because the mean of its divisors is an integer number (11694060).

Almost surely, 2^42878209 is an apocalyptic number.

It is an amenable number.

42878209 is a deficient number, since it is larger than the sum of its proper divisors (3898031).

42878209 is a wasteful number, since it uses less digits than its factorization.

42878209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3898030.

The product of its (nonzero) digits is 64512, while the sum is 40.

The square root of 42878209 is about 6548.1454626482. The cubic root of 42878209 is about 350.0087317549.

The spelling of 42878209 in words is "forty-two million, eight hundred seventy-eight thousand, two hundred nine".