128305821 has 16 divisors (see below), whose sum is σ = 196532864. Its totient is φ = 72935424.

The previous prime is 128305819. The next prime is 128305829. The reversal of 128305821 is 128503821.

It is not a de Polignac number, because 128305821 - 2¹ = 128305819 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128305829) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11776 + ... + 19881.

It is an arithmetic number, because the mean of its divisors is an integer number (12283304).

Almost surely, 2^128305821 is an apocalyptic number.

It is an amenable number.

128305821 is a deficient number, since it is larger than the sum of its proper divisors (68227043).

128305821 is a wasteful number, since it uses less digits than its factorization.

128305821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31860.

The product of its (nonzero) digits is 3840, while the sum is 30.

The square root of 128305821 is about 11327.2159421457. The cubic root of 128305821 is about 504.3694656429.

The spelling of 128305821 in words is "one hundred twenty-eight million, three hundred five thousand, eight hundred twenty-one".