205842139 has 4 divisors (see below), whose sum is σ = 212482240. Its totient is φ = 199202040.

The previous prime is 205842127. The next prime is 205842149. The reversal of 205842139 is 931248502.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 931248502 = 2 ⋅465624251.

It is a cyclic number.

It is not a de Polignac number, because 205842139 - 2¹⁹ = 205317851 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (205842149) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3320004 + ... + 3320065.

It is an arithmetic number, because the mean of its divisors is an integer number (53120560).

Almost surely, 2^205842139 is an apocalyptic number.

205842139 is a deficient number, since it is larger than the sum of its proper divisors (6640101).

205842139 is an equidigital number, since it uses as much as digits as its factorization.

205842139 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6640100.

The product of its (nonzero) digits is 17280, while the sum is 34.

The square root of 205842139 is about 14347.1996919259. The cubic root of 205842139 is about 590.4431593434.

The spelling of 205842139 in words is "two hundred five million, eight hundred forty-two thousand, one hundred thirty-nine".