128023531 has 4 divisors (see below), whose sum is σ = 129777352. Its totient is φ = 126269712.

The previous prime is 128023517. The next prime is 128023559. The reversal of 128023531 is 135320821.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 135320821 = 593 ⋅228197.

It is a cyclic number.

It is not a de Polignac number, because 128023531 - 2⁵ = 128023499 is a prime.

It is a super-2 number, since 2×128023531² = 32780048979415922, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 128023496 and 128023505.

It is not an unprimeable number, because it can be changed into a prime (128023561) 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, 876801 + ... + 876946.

It is an arithmetic number, because the mean of its divisors is an integer number (32444338).

Almost surely, 2^128023531 is an apocalyptic number.

128023531 is a deficient number, since it is larger than the sum of its proper divisors (1753821).

128023531 is an equidigital number, since it uses as much as digits as its factorization.

128023531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1753820.

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 128023531 is about 11314.7483842991. The cubic root of 128023531 is about 503.9993005680. Note that the first 3 decimals are identical.

The spelling of 128023531 in words is "one hundred twenty-eight million, twenty-three thousand, five hundred thirty-one".