139409 has 2 divisors, whose sum is σ = 139410. Its totient is φ = 139408.

The previous prime is 139397. The next prime is 139423. The reversal of 139409 is 904931.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 78400 + 61009 = 280^2 + 247^2 .

It is an emirp because it is prime and its reverse (904931) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 139409 - 2⁴ = 139393 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is equal to p₁₂₉₅₉ and since 139409 and 12959 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (139429) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69704 + 69705.

It is an arithmetic number, because the mean of its divisors is an integer number (69705).

2¹³⁹⁴⁰⁹ is an apocalyptic number.

It is an amenable number.

139409 is a deficient number, since it is larger than the sum of its proper divisors (1).

139409 is an equidigital number, since it uses as much as digits as its factorization.

139409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 972, while the sum is 26.

The square root of 139409 is about 373.3751464680. The cubic root of 139409 is about 51.8517721528.

The spelling of 139409 in words is "one hundred thirty-nine thousand, four hundred nine".