128204021 has 16 divisors (see below), whose sum is σ = 148443840. Its totient is φ = 109428480.

The previous prime is 128204017. The next prime is 128204051. The reversal of 128204021 is 120402821.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 128204021 - 2² = 128204017 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 128203984 and 128204002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128204051) 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, 154235 + ... + 155063.

It is an arithmetic number, because the mean of its divisors is an integer number (9277740).

Almost surely, 2^128204021 is an apocalyptic number.

128204021 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

128204021 is a deficient number, since it is larger than the sum of its proper divisors (20239819).

128204021 is a wasteful number, since it uses less digits than its factorization.

128204021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1684.

The product of its (nonzero) digits is 256, while the sum is 20.

The square root of 128204021 is about 11322.7214484858. The cubic root of 128204021 is about 504.2360386051.

Adding to 128204021 its reverse (120402821), we get a palindrome (248606842).

The spelling of 128204021 in words is "one hundred twenty-eight million, two hundred four thousand, twenty-one".