128642187 has 4 divisors (see below), whose sum is σ = 171522920. Its totient is φ = 85761456.

The previous prime is 128642177. The next prime is 128642191. The reversal of 128642187 is 781246821.

It is a happy number.

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

It is not a de Polignac number, because 128642187 - 2⁶ = 128642123 is a prime.

It is a super-2 number, since 2×128642187² = 33097624552285938, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (128642167) 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, 21440362 + ... + 21440367.

It is an arithmetic number, because the mean of its divisors is an integer number (42880730).

Almost surely, 2^128642187 is an apocalyptic number.

128642187 is a deficient number, since it is larger than the sum of its proper divisors (42880733).

128642187 is an equidigital number, since it uses as much as digits as its factorization.

128642187 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42880732.

The product of its digits is 43008, while the sum is 39.

The square root of 128642187 is about 11342.0539145254. The cubic root of 128642187 is about 504.8098320016.

It can be divided in two parts, 12864 and 2187, that added together give a palindrome (15051).

The spelling of 128642187 in words is "one hundred twenty-eight million, six hundred forty-two thousand, one hundred eighty-seven".