128939689 has 2 divisors, whose sum is σ = 128939690. Its totient is φ = 128939688.

The previous prime is 128939669. The next prime is 128939743. The reversal of 128939689 is 986939821.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 126787600 + 2152089 = 11260^2 + 1467^2 .

It is a cyclic number.

It is not a de Polignac number, because 128939689 - 2¹³ = 128931497 is a prime.

It is not a weakly prime, because it can be changed into another prime (128939609) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64469844 + 64469845.

It is an arithmetic number, because the mean of its divisors is an integer number (64469845).

Almost surely, 2^128939689 is an apocalyptic number.

It is an amenable number.

128939689 is a deficient number, since it is larger than the sum of its proper divisors (1).

128939689 is an equidigital number, since it uses as much as digits as its factorization.

128939689 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1679616, while the sum is 55.

The square root of 128939689 is about 11355.1613374712. The cubic root of 128939689 is about 505.1986788095.

The spelling of 128939689 in words is "one hundred twenty-eight million, nine hundred thirty-nine thousand, six hundred eighty-nine".