128917979 has 2 divisors, whose sum is σ = 128917980. Its totient is φ = 128917978.

The previous prime is 128917939. The next prime is 128918011. The reversal of 128917979 is 979719821.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 128917979 - 2¹⁶ = 128852443 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 128917979.

It is not a weakly prime, because it can be changed into another prime (128917939) 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, 64458989 + 64458990.

It is an arithmetic number, because the mean of its divisors is an integer number (64458990).

Almost surely, 2^128917979 is an apocalyptic number.

128917979 is a deficient number, since it is larger than the sum of its proper divisors (1).

128917979 is an equidigital number, since it uses as much as digits as its factorization.

128917979 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 571536, while the sum is 53.

The square root of 128917979 is about 11354.2053442766. The cubic root of 128917979 is about 505.1703232296.

The spelling of 128917979 in words is "one hundred twenty-eight million, nine hundred seventeen thousand, nine hundred seventy-nine".