128821819 has 8 divisors (see below), whose sum is σ = 147875328. Its totient is φ = 109930920.

The previous prime is 128821817. The next prime is 128821831. The reversal of 128821819 is 918128821.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 128821819 - 2¹ = 128821817 is a prime.

It is a super-2 number, since 2×128821819² = 33190122100937522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (128821811) 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 7 ways as a sum of consecutive naturals, for example, 38947 + ... + 42124.

It is an arithmetic number, because the mean of its divisors is an integer number (18484416).

Almost surely, 2^128821819 is an apocalyptic number.

128821819 is a deficient number, since it is larger than the sum of its proper divisors (19053509).

128821819 is an equidigital number, since it uses as much as digits as its factorization.

128821819 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 81305.

The product of its digits is 18432, while the sum is 40.

The square root of 128821819 is about 11349.9699999604. The cubic root of 128821819 is about 505.0446897026.

The spelling of 128821819 in words is "one hundred twenty-eight million, eight hundred twenty-one thousand, eight hundred nineteen".