128572921 has 27 divisors (see below), whose sum is σ = 147870541. Its totient is φ = 111757184.

The previous prime is 128572909. The next prime is 128572949. The reversal of 128572921 is 129275821.

The square root of 128572921 is 11339.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 12709225 + 115863696 = 3565^2 + 10764^2 .

It is not a de Polignac number, because 128572921 - 2⁵ = 128572889 is a prime.

It is a super-3 number, since 3×128572921³ (a number of 25 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (128572991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 4433535 + ... + 4433563.

Almost surely, 2^128572921 is an apocalyptic number.

128572921 is the 11339-th square number.

128572921 is the 5670-th centered octagonal number.

It is an amenable number.

128572921 is a deficient number, since it is larger than the sum of its proper divisors (19297620).

128572921 is an equidigital number, since it uses as much as digits as its factorization.

128572921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 138 (or 69 counting only the distinct ones).

The product of its digits is 20160, while the sum is 37.

The cubic root of 128572921 is about 504.7192125964.

It can be divided in two parts, 128 and 572921, that added together give a square (573049 = 757²).

The spelling of 128572921 in words is "one hundred twenty-eight million, five hundred seventy-two thousand, nine hundred twenty-one".