21103128 has 24 divisors (see below), whose sum is σ = 57154500. Its totient is φ = 7034352.

The previous prime is 21103127. The next prime is 21103139. The reversal of 21103128 is 82130112.

It is a tau number, because it is divible by the number of its divisors (24).

It is a super-2 number, since 2×21103128² = 890684022768768, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a self number, because there is not a number n which added to its sum of digits gives 21103128.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21103123) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 146478 + ... + 146621.

Almost surely, 2^21103128 is an apocalyptic number.

It is an amenable number.

21103128 is an abundant number, since it is smaller than the sum of its proper divisors (36051372).

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

21103128 is a wasteful number, since it uses less digits than its factorization.

21103128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 293111 (or 293104 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 18.

The square root of 21103128 is about 4593.8141015936. The cubic root of 21103128 is about 276.3433031135.

The spelling of 21103128 in words is "twenty-one million, one hundred three thousand, one hundred twenty-eight".