128626821 has 12 divisors (see below), whose sum is σ = 185923660. Its totient is φ = 85691520.

The previous prime is 128626769. The next prime is 128626829.

128626821 is a `hidden beast` number, since 1 + 2 + 8 + 626 + 8 + 21 = 666.

128626821 is nontrivially palindromic in base 10.

It can be written as a sum of positive squares in 2 ways, for example, as 2873025 + 125753796 = 1695^2 + 11214^2 .

It is not a de Polignac number, because 128626821 - 2¹⁴ = 128610437 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128626829) 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 11 ways as a sum of consecutive naturals, for example, 11565 + ... + 19773.

Almost surely, 2^128626821 is an apocalyptic number.

It is an amenable number.

128626821 is a deficient number, since it is larger than the sum of its proper divisors (57296839).

128626821 is a wasteful number, since it uses less digits than its factorization.

128626821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9956 (or 9953 counting only the distinct ones).

The product of its digits is 18432, while the sum is 36.

The square root of 128626821 is about 11341.3765037583. The cubic root of 128626821 is about 504.7897317609.

It can be divided in two parts, 12862 and 6821, that added together give a 9-th power (19683 = 3⁹).

The spelling of 128626821 in words is "one hundred twenty-eight million, six hundred twenty-six thousand, eight hundred twenty-one".