21660128 has 24 divisors (see below), whose sum is σ = 48735792. Its totient is φ = 9282816.

The previous prime is 21660127. The next prime is 21660131. The reversal of 21660128 is 82106612.

It is a super-2 number, since 2×21660128² = 938322289952768, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21660097 and 21660106.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21660127) 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, 48125 + ... + 48572.

It is an arithmetic number, because the mean of its divisors is an integer number (2030658).

Almost surely, 2^21660128 is an apocalyptic number.

21660128 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21660128 is an abundant number, since it is smaller than the sum of its proper divisors (27075664).

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

21660128 is an equidigital number, since it uses as much as digits as its factorization.

21660128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 96714 (or 96706 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 26.

The square root of 21660128 is about 4654.0442627891. The cubic root of 21660128 is about 278.7535067628.

The spelling of 21660128 in words is "twenty-one million, six hundred sixty thousand, one hundred twenty-eight".