642209 has 8 divisors (see below), whose sum is σ = 699048. Its totient is φ = 587520.

The previous prime is 642199. The next prime is 642211. The reversal of 642209 is 902246.

It can be written as a sum of positive squares in 4 ways, for example, as 336400 + 305809 = 580^2 + 553^2 .

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

It is a de Polignac number, because none of the positive numbers 2^k-642209 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (642809) 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, 119 + ... + 1139.

It is an arithmetic number, because the mean of its divisors is an integer number (87381).

2⁶⁴²²⁰⁹ is an apocalyptic number.

It is an amenable number.

642209 is a deficient number, since it is larger than the sum of its proper divisors (56839).

642209 is a wasteful number, since it uses less digits than its factorization.

642209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1075.

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 642209 is about 801.3794357232. The cubic root of 642209 is about 86.2764226265.

It can be divided in two parts, 64 and 2209, that multiplied together give a square (141376 = 376²).

The spelling of 642209 in words is "six hundred forty-two thousand, two hundred nine".