128651 has 4 divisors (see below), whose sum is σ = 129792. Its totient is φ = 127512.

The previous prime is 128629. The next prime is 128657. The reversal of 128651 is 156821.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-128651 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (128657) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 380 + ... + 633.

It is an arithmetic number, because the mean of its divisors is an integer number (32448).

2¹²⁸⁶⁵¹ is an apocalyptic number.

128651 is a deficient number, since it is larger than the sum of its proper divisors (1141).

128651 is a wasteful number, since it uses less digits than its factorization.

128651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1140.

The product of its digits is 480, while the sum is 23.

The square root of 128651 is about 358.6795226940. The cubic root of 128651 is about 50.4821359551.

The spelling of 128651 in words is "one hundred twenty-eight thousand, six hundred fifty-one".