100128409 has 4 divisors (see below), whose sum is σ = 100892880. Its totient is φ = 99363940.

The previous prime is 100128397. The next prime is 100128439. The reversal of 100128409 is 904821001.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 904821001 = 7 ⋅129260143.

It is a cyclic number.

It is not a de Polignac number, because 100128409 - 2²¹ = 98031257 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (100128439) 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, 382039 + ... + 382300.

It is an arithmetic number, because the mean of its divisors is an integer number (25223220).

Almost surely, 2^100128409 is an apocalyptic number.

It is an amenable number.

100128409 is a deficient number, since it is larger than the sum of its proper divisors (764471).

100128409 is an equidigital number, since it uses as much as digits as its factorization.

100128409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 764470.

The product of its (nonzero) digits is 576, while the sum is 25.

The square root of 100128409 is about 10006.4183902134. The cubic root of 100128409 is about 464.3574723103.

The spelling of 100128409 in words is "one hundred million, one hundred twenty-eight thousand, four hundred nine".