128938521 has 4 divisors (see below), whose sum is σ = 171918032. Its totient is φ = 85959012.

The previous prime is 128938501. The next prime is 128938543. The reversal of 128938521 is 125839821.

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 not a de Polignac number, because 128938521 - 2¹¹ = 128936473 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 128938521.

It is not an unprimeable number, because it can be changed into a prime (128938501) 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, 21489751 + ... + 21489756.

It is an arithmetic number, because the mean of its divisors is an integer number (42979508).

Almost surely, 2^128938521 is an apocalyptic number.

It is an amenable number.

128938521 is a deficient number, since it is larger than the sum of its proper divisors (42979511).

128938521 is an equidigital number, since it uses as much as digits as its factorization.

128938521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42979510.

The product of its digits is 34560, while the sum is 39.

The square root of 128938521 is about 11355.1099069978. The cubic root of 128938521 is about 505.1971533577.

The spelling of 128938521 in words is "one hundred twenty-eight million, nine hundred thirty-eight thousand, five hundred twenty-one".