128443921 has 2 divisors, whose sum is σ = 128443922. Its totient is φ = 128443920.

The previous prime is 128443907. The next prime is 128443927. The reversal of 128443921 is 129344821.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 104775696 + 23668225 = 10236^2 + 4865^2 .

It is an emirp because it is prime and its reverse (129344821) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 128443921 - 2¹³ = 128435729 is a prime.

It is not a weakly prime, because it can be changed into another prime (128443927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64221960 + 64221961.

It is an arithmetic number, because the mean of its divisors is an integer number (64221961).

Almost surely, 2^128443921 is an apocalyptic number.

It is an amenable number.

128443921 is a deficient number, since it is larger than the sum of its proper divisors (1).

128443921 is an equidigital number, since it uses as much as digits as its factorization.

128443921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 13824, while the sum is 34.

The square root of 128443921 is about 11333.3102401726. The cubic root of 128443921 is about 504.5503575345.

The spelling of 128443921 in words is "one hundred twenty-eight million, four hundred forty-three thousand, nine hundred twenty-one".