21208128 has 28 divisors (see below), whose sum is σ = 56113680. Its totient is φ = 7069312.

The previous prime is 21208127. The next prime is 21208133. The reversal of 21208128 is 82180212.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a junction number, because it is equal to n+sod(n) for n = 21208098 and 21208107.

It is not an unprimeable number, because it can be changed into a prime (21208127) 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, 55038 + ... + 55421.

It is an arithmetic number, because the mean of its divisors is an integer number (2004060).

Almost surely, 2^21208128 is an apocalyptic number.

It is an amenable number.

21208128 is an abundant number, since it is smaller than the sum of its proper divisors (34905552).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21208128 is a wasteful number, since it uses less digits than its factorization.

21208128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 110474 (or 110464 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 24.

The square root of 21208128 is about 4605.2283331014. The cubic root of 21208128 is about 276.8008664924.

The spelling of 21208128 in words is "twenty-one million, two hundred eight thousand, one hundred twenty-eight".