128431139 has 2 divisors, whose sum is σ = 128431140. Its totient is φ = 128431138.

The previous prime is 128431117. The next prime is 128431151. The reversal of 128431139 is 931134821.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-128431139 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (128431159) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64215569 + 64215570.

It is an arithmetic number, because the mean of its divisors is an integer number (64215570).

Almost surely, 2^128431139 is an apocalyptic number.

128431139 is a deficient number, since it is larger than the sum of its proper divisors (1).

128431139 is an equidigital number, since it uses as much as digits as its factorization.

128431139 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5184, while the sum is 32.

The square root of 128431139 is about 11332.7463132288. The cubic root of 128431139 is about 504.5336203298.

It can be divided in two parts, 1284 and 31139, that added together give a palindrome (32423).

The spelling of 128431139 in words is "one hundred twenty-eight million, four hundred thirty-one thousand, one hundred thirty-nine".