128821553 has 4 divisors (see below), whose sum is σ = 147224640. Its totient is φ = 110418468.

The previous prime is 128821547. The next prime is 128821607. The reversal of 128821553 is 355128821.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 355128821 = 11981 ⋅29641.

It is a cyclic number.

It is not a de Polignac number, because 128821553 - 2¹⁰ = 128820529 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (128821513) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9201533 + ... + 9201546.

It is an arithmetic number, because the mean of its divisors is an integer number (36806160).

Almost surely, 2^128821553 is an apocalyptic number.

It is an amenable number.

128821553 is a deficient number, since it is larger than the sum of its proper divisors (18403087).

128821553 is an equidigital number, since it uses as much as digits as its factorization.

128821553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18403086.

The product of its digits is 19200, while the sum is 35.

The square root of 128821553 is about 11349.9582818617. The cubic root of 128821553 is about 505.0443420855.

The spelling of 128821553 in words is "one hundred twenty-eight million, eight hundred twenty-one thousand, five hundred fifty-three".