128021717 has 4 divisors (see below), whose sum is σ = 128102316. Its totient is φ = 127941120.

The previous prime is 128021701. The next prime is 128021743. The reversal of 128021717 is 717120821.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 119224561 + 8797156 = 10919^2 + 2966^2 .

It is a cyclic number.

It is not a de Polignac number, because 128021717 - 2⁴ = 128021701 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 128021717.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128321717) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 37868 + ... + 41109.

It is an arithmetic number, because the mean of its divisors is an integer number (32025579).

Almost surely, 2^128021717 is an apocalyptic number.

It is an amenable number.

128021717 is a deficient number, since it is larger than the sum of its proper divisors (80599).

128021717 is an equidigital number, since it uses as much as digits as its factorization.

128021717 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80598.

The product of its (nonzero) digits is 1568, while the sum is 29.

The square root of 128021717 is about 11314.6682231518. The cubic root of 128021717 is about 503.9969201227.

The spelling of 128021717 in words is "one hundred twenty-eight million, twenty-one thousand, seven hundred seventeen".