128821025 has 6 divisors (see below), whose sum is σ = 159738102. Its totient is φ = 103056800.

The previous prime is 128821001. The next prime is 128821039. The reversal of 128821025 is 520128821.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 134689 + 128686336 = 367^2 + 11344^2 .

It is not a de Polignac number, because 128821025 - 2¹² = 128816929 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2576396 + ... + 2576445.

It is an arithmetic number, because the mean of its divisors is an integer number (26623017).

Almost surely, 2^128821025 is an apocalyptic number.

It is an amenable number.

128821025 is a deficient number, since it is larger than the sum of its proper divisors (30917077).

128821025 is an equidigital number, since it uses as much as digits as its factorization.

128821025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5152851 (or 5152846 counting only the distinct ones).

The product of its (nonzero) digits is 2560, while the sum is 29.

The square root of 128821025 is about 11349.9350218404. The cubic root of 128821025 is about 505.0436520773.

Adding to 128821025 its reverse (520128821), we get a palindrome (648949846).

The spelling of 128821025 in words is "one hundred twenty-eight million, eight hundred twenty-one thousand, twenty-five".