21728108 has 24 divisors (see below), whose sum is σ = 40515552. Its totient is φ = 10160384.

The previous prime is 21728101. The next prime is 21728111. The reversal of 21728108 is 80182712.

It is a super-2 number, since 2×21728108² = 944221354519328, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21728101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10841 + ... + 12687.

It is an arithmetic number, because the mean of its divisors is an integer number (1688148).

Almost surely, 2^21728108 is an apocalyptic number.

It is an amenable number.

21728108 is a deficient number, since it is larger than the sum of its proper divisors (18787444).

21728108 is a wasteful number, since it uses less digits than its factorization.

21728108 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2041 (or 2039 counting only the distinct ones).

The product of its (nonzero) digits is 1792, while the sum is 29.

The square root of 21728108 is about 4661.3418668877. The cubic root of 21728108 is about 279.0448235003.

The spelling of 21728108 in words is "twenty-one million, seven hundred twenty-eight thousand, one hundred eight".