642086809 has 8 divisors (see below), whose sum is σ = 790260800. Its totient is φ = 508024656.

The previous prime is 642086771. The next prime is 642086813. The reversal of 642086809 is 908680246.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 642086809 - 2¹⁵ = 642054041 is a prime.

It is not an unprimeable number, because it can be changed into a prime (642086839) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3527859 + ... + 3528040.

It is an arithmetic number, because the mean of its divisors is an integer number (98782600).

Almost surely, 2^642086809 is an apocalyptic number.

It is an amenable number.

642086809 is a deficient number, since it is larger than the sum of its proper divisors (148173991).

642086809 is a wasteful number, since it uses less digits than its factorization.

642086809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7055919.

The product of its (nonzero) digits is 165888, while the sum is 43.

The square root of 642086809 is about 25339.4318997092. The cubic root of 642086809 is about 862.7095043540.

It can be divided in two parts, 64208 and 6809, that added together give a palindrome (71017).

The spelling of 642086809 in words is "six hundred forty-two million, eighty-six thousand, eight hundred nine".