128023521 has 16 divisors (see below), whose sum is σ = 176517120. Its totient is φ = 82449360.

The previous prime is 128023517. The next prime is 128023559. The reversal of 128023521 is 125320821.

It is not a de Polignac number, because 128023521 - 2² = 128023517 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 128023491 and 128023500.

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 15 ways as a sum of consecutive naturals, for example, 81340 + ... + 82898.

It is an arithmetic number, because the mean of its divisors is an integer number (11032320).

Almost surely, 2^128023521 is an apocalyptic number.

It is an amenable number.

128023521 is a deficient number, since it is larger than the sum of its proper divisors (48493599).

128023521 is a wasteful number, since it uses less digits than its factorization.

128023521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2476.

The product of its (nonzero) digits is 960, while the sum is 24.

The square root of 128023521 is about 11314.7479423980. The cubic root of 128023521 is about 503.9992874455. Note that the first 3 decimals are identical.

The spelling of 128023521 in words is "one hundred twenty-eight million, twenty-three thousand, five hundred twenty-one".