42856109 has 2 divisors, whose sum is σ = 42856110. Its totient is φ = 42856108.

The previous prime is 42856091. The next prime is 42856117. The reversal of 42856109 is 90165824.

Together with previous prime (42856091) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 23522500 + 19333609 = 4850^2 + 4397^2 .

It is a cyclic number.

It is not a de Polignac number, because 42856109 - 2²⁰ = 41807533 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (42856169) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21428054 + 21428055.

It is an arithmetic number, because the mean of its divisors is an integer number (21428055).

Almost surely, 2^42856109 is an apocalyptic number.

It is an amenable number.

42856109 is a deficient number, since it is larger than the sum of its proper divisors (1).

42856109 is an equidigital number, since it uses as much as digits as its factorization.

42856109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 17280, while the sum is 35.

The square root of 42856109 is about 6546.4577444600. The cubic root of 42856109 is about 349.9485883669.

The spelling of 42856109 in words is "forty-two million, eight hundred fifty-six thousand, one hundred nine".