128609749 has 2 divisors, whose sum is σ = 128609750. Its totient is φ = 128609748.

The previous prime is 128609737. The next prime is 128609779. The reversal of 128609749 is 947906821.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 67535524 + 61074225 = 8218^2 + 7815^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-128609749 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 128609699 and 128609708.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (128609729) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64304874 + 64304875.

It is an arithmetic number, because the mean of its divisors is an integer number (64304875).

Almost surely, 2^128609749 is an apocalyptic number.

It is an amenable number.

128609749 is a deficient number, since it is larger than the sum of its proper divisors (1).

128609749 is an equidigital number, since it uses as much as digits as its factorization.

128609749 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 217728, while the sum is 46.

The square root of 128609749 is about 11340.6238364563. The cubic root of 128609749 is about 504.7673980270.

The spelling of 128609749 in words is "one hundred twenty-eight million, six hundred nine thousand, seven hundred forty-nine".