128388431 has 4 divisors (see below), whose sum is σ = 129157392. Its totient is φ = 127619472.

The previous prime is 128388413. The next prime is 128388433. The reversal of 128388431 is 134883821.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 134883821 = 31 ⋅4351091.

It is a cyclic number.

It is not a de Polignac number, because 128388431 - 2¹⁰ = 128387407 is a prime.

It is a super-2 number, since 2×128388431² = 32967178429283522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128388433) 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, 384230 + ... + 384563.

It is an arithmetic number, because the mean of its divisors is an integer number (32289348).

Almost surely, 2^128388431 is an apocalyptic number.

128388431 is a deficient number, since it is larger than the sum of its proper divisors (768961).

128388431 is an equidigital number, since it uses as much as digits as its factorization.

128388431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 768960.

The product of its digits is 36864, while the sum is 38.

The square root of 128388431 is about 11330.8618824871. The cubic root of 128388431 is about 504.4776889024.

The spelling of 128388431 in words is "one hundred twenty-eight million, three hundred eighty-eight thousand, four hundred thirty-one".