139247309 has 2 divisors, whose sum is σ = 139247310. Its totient is φ = 139247308.

The previous prime is 139247279. The next prime is 139247321. The reversal of 139247309 is 903742931.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 108222409 + 31024900 = 10403^2 + 5570^2 .

It is a cyclic number.

It is not a de Polignac number, because 139247309 - 2¹² = 139243213 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (139247209) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69623654 + 69623655.

It is an arithmetic number, because the mean of its divisors is an integer number (69623655).

Almost surely, 2^139247309 is an apocalyptic number.

It is an amenable number.

139247309 is a deficient number, since it is larger than the sum of its proper divisors (1).

139247309 is an equidigital number, since it uses as much as digits as its factorization.

139247309 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 40824, while the sum is 38.

The square root of 139247309 is about 11800.3096993257. The cubic root of 139247309 is about 518.3171795184.

The spelling of 139247309 in words is "one hundred thirty-nine million, two hundred forty-seven thousand, three hundred nine".