21156128 has 24 divisors (see below), whose sum is σ = 47601792. Its totient is φ = 9066816.

The previous prime is 21156127. The next prime is 21156131. The reversal of 21156128 is 82165112.

It is a junction number, because it is equal to n+sod(n) for n = 21156097 and 21156106.

It is not an unprimeable number, because it can be changed into a prime (21156127) 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, 47000 + ... + 47447.

It is an arithmetic number, because the mean of its divisors is an integer number (1983408).

Almost surely, 2^21156128 is an apocalyptic number.

21156128 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21156128 is an abundant number, since it is smaller than the sum of its proper divisors (26445664).

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

21156128 is an equidigital number, since it uses as much as digits as its factorization.

21156128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 94464 (or 94456 counting only the distinct ones).

The product of its digits is 960, while the sum is 26.

The square root of 21156128 is about 4599.5791111796. The cubic root of 21156128 is about 276.5744529057.

The spelling of 21156128 in words is "twenty-one million, one hundred fifty-six thousand, one hundred twenty-eight".