128887021 has 4 divisors (see below), whose sum is σ = 132370492. Its totient is φ = 125403552.

The previous prime is 128886959. The next prime is 128887037. The reversal of 128887021 is 120788821.

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 54686025 + 74200996 = 7395^2 + 8614^2 .

It is a cyclic number.

It is not a de Polignac number, because 128887021 - 2⁷ = 128886893 is a prime.

It is a super-2 number, since 2×128887021² = 33223728364508882, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (37), and also a Moran number because the ratio is a prime number: 3483433 = 128887021 / (1 + 2 + 8 + 8 + 8 + 7 + 0 + 2 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128887061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1741680 + ... + 1741753.

It is an arithmetic number, because the mean of its divisors is an integer number (33092623).

Almost surely, 2^128887021 is an apocalyptic number.

It is an amenable number.

128887021 is a deficient number, since it is larger than the sum of its proper divisors (3483471).

128887021 is an equidigital number, since it uses as much as digits as its factorization.

128887021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3483470.

The product of its (nonzero) digits is 14336, while the sum is 37.

The square root of 128887021 is about 11352.8419789936. The cubic root of 128887021 is about 505.1298832667.

The spelling of 128887021 in words is "one hundred twenty-eight million, eight hundred eighty-seven thousand, twenty-one".