139991809 has 2 divisors, whose sum is σ = 139991810. Its totient is φ = 139991808.

The previous prime is 139991779. The next prime is 139991827. The reversal of 139991809 is 908199931.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 93547584 + 46444225 = 9672^2 + 6815^2 .

It is a cyclic number.

It is not a de Polignac number, because 139991809 - 2¹⁵ = 139959041 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (139991849) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69995904 + 69995905.

It is an arithmetic number, because the mean of its divisors is an integer number (69995905).

Almost surely, 2^139991809 is an apocalyptic number.

It is an amenable number.

139991809 is a deficient number, since it is larger than the sum of its proper divisors (1).

139991809 is an equidigital number, since it uses as much as digits as its factorization.

139991809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 157464, while the sum is 49.

The square root of 139991809 is about 11831.8134282112. The cubic root of 139991809 is about 519.2392833878.

The spelling of 139991809 in words is "one hundred thirty-nine million, nine hundred ninety-one thousand, eight hundred nine".