128823531 has 4 divisors (see below), whose sum is σ = 171764712. Its totient is φ = 85882352.

The previous prime is 128823509. The next prime is 128823551. The reversal of 128823531 is 135328821.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-128823531 is a prime.

It is a super-2 number, since 2×128823531² = 33191004278615922, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 128823492 and 128823501.

It is not an unprimeable number, because it can be changed into a prime (128823551) 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, 21470586 + ... + 21470591.

It is an arithmetic number, because the mean of its divisors is an integer number (42941178).

Almost surely, 2^128823531 is an apocalyptic number.

128823531 is a deficient number, since it is larger than the sum of its proper divisors (42941181).

128823531 is an equidigital number, since it uses as much as digits as its factorization.

128823531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42941180.

The product of its digits is 11520, while the sum is 33.

The square root of 128823531 is about 11350.0454184113. The cubic root of 128823531 is about 505.0469269858.

The spelling of 128823531 in words is "one hundred twenty-eight million, eight hundred twenty-three thousand, five hundred thirty-one".