205978139 has 2 divisors, whose sum is σ = 205978140. Its totient is φ = 205978138.

The previous prime is 205978109. The next prime is 205978169. The reversal of 205978139 is 931879502.

It is a balanced prime because it is at equal distance from previous prime (205978109) and next prime (205978169).

It is a cyclic number.

It is not a de Polignac number, because 205978139 - 2⁸ = 205977883 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 205978139.

It is not a weakly prime, because it can be changed into another prime (205978109) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102989069 + 102989070.

It is an arithmetic number, because the mean of its divisors is an integer number (102989070).

Almost surely, 2^205978139 is an apocalyptic number.

205978139 is a deficient number, since it is larger than the sum of its proper divisors (1).

205978139 is an equidigital number, since it uses as much as digits as its factorization.

205978139 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 136080, while the sum is 44.

The square root of 205978139 is about 14351.9385101804. The cubic root of 205978139 is about 590.5731660753.

The spelling of 205978139 in words is "two hundred five million, nine hundred seventy-eight thousand, one hundred thirty-nine".