209942 has 4 divisors (see below), whose sum is σ = 314916. Its totient is φ = 104970.

The previous prime is 209939. The next prime is 209953. The reversal of 209942 is 249902.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 249902 = 2 ⋅124951.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 52484 + ... + 52487.

It is an arithmetic number, because the mean of its divisors is an integer number (78729).

2²⁰⁹⁹⁴² is an apocalyptic number.

209942 is a deficient number, since it is larger than the sum of its proper divisors (104974).

209942 is a wasteful number, since it uses less digits than its factorization.

209942 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 104973.

The product of its (nonzero) digits is 1296, while the sum is 26.

The square root of 209942 is about 458.1942819373. The cubic root of 209942 is about 59.4337468417.

It can be divided in two parts, 209 and 942, that multiplied together give a triangular number (196878 = T₆₂₇).

The spelling of 209942 in words is "two hundred nine thousand, nine hundred forty-two".