128221971 has 4 divisors (see below), whose sum is σ = 170962632. Its totient is φ = 85481312.

The previous prime is 128221967. The next prime is 128221993. The reversal of 128221971 is 179122821.

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

It is a cyclic number.

It is not a de Polignac number, because 128221971 - 2² = 128221967 is a prime.

It is not an unprimeable number, because it can be changed into a prime (128221901) 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, 21370326 + ... + 21370331.

It is an arithmetic number, because the mean of its divisors is an integer number (42740658).

Almost surely, 2^128221971 is an apocalyptic number.

128221971 is a deficient number, since it is larger than the sum of its proper divisors (42740661).

128221971 is an equidigital number, since it uses as much as digits as its factorization.

128221971 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42740660.

The product of its digits is 4032, while the sum is 33.

The square root of 128221971 is about 11323.5140747031. The cubic root of 128221971 is about 504.2595704061.

The spelling of 128221971 in words is "one hundred twenty-eight million, two hundred twenty-one thousand, nine hundred seventy-one".