642109 has 4 divisors (see below), whose sum is σ = 691516. Its totient is φ = 592704.

The previous prime is 642079. The next prime is 642113. The reversal of 642109 is 901246.

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

It can be written as a sum of positive squares in 2 ways, for example, as 308025 + 334084 = 555^2 + 578^2 .

It is a cyclic number.

It is not a de Polignac number, because 642109 - 2⁵ = 642077 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 642109.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642149) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24684 + ... + 24709.

It is an arithmetic number, because the mean of its divisors is an integer number (172879).

2⁶⁴²¹⁰⁹ is an apocalyptic number.

It is an amenable number.

642109 is a deficient number, since it is larger than the sum of its proper divisors (49407).

642109 is a wasteful number, since it uses less digits than its factorization.

642109 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49406.

The product of its (nonzero) digits is 432, while the sum is 22.

The square root of 642109 is about 801.3170408771. The cubic root of 642109 is about 86.2719442868.

The spelling of 642109 in words is "six hundred forty-two thousand, one hundred nine".