128021573 has 4 divisors (see below), whose sum is σ = 132436140. Its totient is φ = 123607008.

The previous prime is 128021549. The next prime is 128021587. The reversal of 128021573 is 375120821.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 87291649 + 40729924 = 9343^2 + 6382^2 .

It is a cyclic number.

It is not a de Polignac number, because 128021573 - 2²⁰ = 126972997 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (29), and also a Moran number because the ratio is a prime number: 4414537 = 128021573 / (1 + 2 + 8 + 0 + 2 + 1 + 5 + 7 + 3).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128021503) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2207240 + ... + 2207297.

It is an arithmetic number, because the mean of its divisors is an integer number (33109035).

Almost surely, 2^128021573 is an apocalyptic number.

It is an amenable number.

128021573 is a deficient number, since it is larger than the sum of its proper divisors (4414567).

128021573 is an equidigital number, since it uses as much as digits as its factorization.

128021573 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4414566.

The product of its (nonzero) digits is 3360, while the sum is 29.

The square root of 128021573 is about 11314.6618597287. The cubic root of 128021573 is about 503.9967311558.

The spelling of 128021573 in words is "one hundred twenty-eight million, twenty-one thousand, five hundred seventy-three".