128531389 has 4 divisors (see below), whose sum is σ = 146893024. Its totient is φ = 110169756.

The previous prime is 128531387. The next prime is 128531399. The reversal of 128531389 is 983135821.

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.

It is a cyclic number.

It is not a de Polignac number, because 128531389 - 2¹ = 128531387 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128531387) 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, 9180807 + ... + 9180820.

It is an arithmetic number, because the mean of its divisors is an integer number (36723256).

Almost surely, 2^128531389 is an apocalyptic number.

It is an amenable number.

128531389 is a deficient number, since it is larger than the sum of its proper divisors (18361635).

128531389 is an equidigital number, since it uses as much as digits as its factorization.

128531389 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18361634.

The product of its digits is 51840, while the sum is 40.

The square root of 128531389 is about 11337.1684736534. The cubic root of 128531389 is about 504.6648614529.

The spelling of 128531389 in words is "one hundred twenty-eight million, five hundred thirty-one thousand, three hundred eighty-nine".