642108639 has 4 divisors (see below), whose sum is σ = 856144856. Its totient is φ = 428072424.

The previous prime is 642108587. The next prime is 642108661. The reversal of 642108639 is 936801246.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 642108639 - 2⁹ = 642108127 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 642108597 and 642108606.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642108739) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 107018104 + ... + 107018109.

It is an arithmetic number, because the mean of its divisors is an integer number (214036214).

Almost surely, 2^642108639 is an apocalyptic number.

642108639 is a deficient number, since it is larger than the sum of its proper divisors (214036217).

642108639 is a wasteful number, since it uses less digits than its factorization.

642108639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 214036216.

The product of its (nonzero) digits is 62208, while the sum is 39.

The square root of 642108639 is about 25339.8626476151. The cubic root of 642108639 is about 862.7192811915.

The spelling of 642108639 in words is "six hundred forty-two million, one hundred eight thousand, six hundred thirty-nine".