209842 has 8 divisors (see below), whose sum is σ = 316800. Its totient is φ = 104244.

The previous prime is 209837. The next prime is 209851. The reversal of 209842 is 248902.

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

It is an Ulam number.

It is a plaindrome in base 14.

It is an unprimeable number.

209842 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 259 + ... + 697.

It is an arithmetic number, because the mean of its divisors is an integer number (39600).

2²⁰⁹⁸⁴² is an apocalyptic number.

209842 is a deficient number, since it is larger than the sum of its proper divisors (106958).

209842 is a wasteful number, since it uses less digits than its factorization.

209842 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 680.

The product of its (nonzero) digits is 1152, while the sum is 25.

The square root of 209842 is about 458.0851449240. The cubic root of 209842 is about 59.4243088086.

Subtracting 209842 from its reverse (248902), we obtain a triangular number (39060 = T₂₇₉).

The spelling of 209842 in words is "two hundred nine thousand, eight hundred forty-two".