128411721 has 12 divisors (see below), whose sum is σ = 185867760. Its totient is φ = 85430520.

The previous prime is 128411687. The next prime is 128411729. The reversal of 128411721 is 127114821.

It is not a de Polignac number, because 128411721 - 2¹⁰ = 128410697 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (128411729) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 10111 + ... + 18948.

It is an arithmetic number, because the mean of its divisors is an integer number (15488980).

Almost surely, 2^128411721 is an apocalyptic number.

It is an amenable number.

128411721 is a deficient number, since it is larger than the sum of its proper divisors (57456039).

128411721 is a wasteful number, since it uses less digits than its factorization.

128411721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29556 (or 29553 counting only the distinct ones).

The product of its digits is 896, while the sum is 27.

The square root of 128411721 is about 11331.8895599984. The cubic root of 128411721 is about 504.5081915859.

The spelling of 128411721 in words is "one hundred twenty-eight million, four hundred eleven thousand, seven hundred twenty-one".