42101809 has 6 divisors (see below), whose sum is σ = 44724374. Its totient is φ = 39624960.

The previous prime is 42101803. The next prime is 42101821. The reversal of 42101809 is 90810124.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 4928400 + 37173409 = 2220^2 + 6097^2 .

It is not a de Polignac number, because 42101809 - 2⁷ = 42101681 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (42101803) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 72552 + ... + 73129.

Almost surely, 2^42101809 is an apocalyptic number.

It is an amenable number.

42101809 is a deficient number, since it is larger than the sum of its proper divisors (2622565).

42101809 is a wasteful number, since it uses less digits than its factorization.

42101809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 145715 (or 145698 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 25.

The square root of 42101809 is about 6488.5906790304. The cubic root of 42101809 is about 347.8833035637.

The spelling of 42101809 in words is "forty-two million, one hundred one thousand, eight hundred nine".