42778609 has 2 divisors, whose sum is σ = 42778610. Its totient is φ = 42778608.

The previous prime is 42778607. The next prime is 42778627. The reversal of 42778609 is 90687724.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 31888609 + 10890000 = 5647^2 + 3300^2 .

It is a cyclic number.

It is not a de Polignac number, because 42778609 - 2¹ = 42778607 is a prime.

Together with 42778607, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (42778607) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21389304 + 21389305.

It is an arithmetic number, because the mean of its divisors is an integer number (21389305).

Almost surely, 2^42778609 is an apocalyptic number.

It is an amenable number.

42778609 is a deficient number, since it is larger than the sum of its proper divisors (1).

42778609 is an equidigital number, since it uses as much as digits as its factorization.

42778609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 169344, while the sum is 43.

The square root of 42778609 is about 6540.5358343182. The cubic root of 42778609 is about 349.7375147610.

The spelling of 42778609 in words is "forty-two million, seven hundred seventy-eight thousand, six hundred nine".