128261389 has 4 divisors (see below), whose sum is σ = 131244256. Its totient is φ = 125278524.

The previous prime is 128261387. The next prime is 128261401. The reversal of 128261389 is 983162821.

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 128261389 - 2¹ = 128261387 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128261387) 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, 1491369 + ... + 1491454.

It is an arithmetic number, because the mean of its divisors is an integer number (32811064).

Almost surely, 2^128261389 is an apocalyptic number.

It is an amenable number.

128261389 is a deficient number, since it is larger than the sum of its proper divisors (2982867).

128261389 is an equidigital number, since it uses as much as digits as its factorization.

128261389 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2982866.

The product of its digits is 41472, while the sum is 40.

The square root of 128261389 is about 11325.2544783771. The cubic root of 128261389 is about 504.3112382731.

The spelling of 128261389 in words is "one hundred twenty-eight million, two hundred sixty-one thousand, three hundred eighty-nine".