128400191 has 4 divisors (see below), whose sum is σ = 133982832. Its totient is φ = 122817552.

The previous prime is 128400179. The next prime is 128400227. The reversal of 128400191 is 191004821.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 191004821 = 7 ⋅27286403.

It is a cyclic number.

It is not a de Polignac number, because 128400191 - 2⁶ = 128400127 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 128400191.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128400131) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2791286 + ... + 2791331.

It is an arithmetic number, because the mean of its divisors is an integer number (33495708).

Almost surely, 2^128400191 is an apocalyptic number.

128400191 is a deficient number, since it is larger than the sum of its proper divisors (5582641).

128400191 is an equidigital number, since it uses as much as digits as its factorization.

128400191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5582640.

The product of its (nonzero) digits is 576, while the sum is 26.

The square root of 128400191 is about 11331.3808072979. The cubic root of 128400191 is about 504.4930913195.

The spelling of 128400191 in words is "one hundred twenty-eight million, four hundred thousand, one hundred ninety-one".