21427128 has 48 divisors (see below), whose sum is σ = 58476600. Its totient is φ = 7087680.

The previous prime is 21427127. The next prime is 21427129. The reversal of 21427128 is 82172412.

It is an interprime number because it is at equal distance from previous prime (21427127) and next prime (21427129).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21427121) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8938 + ... + 11078.

Almost surely, 2^21427128 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21427128, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29238300).

21427128 is an abundant number, since it is smaller than the sum of its proper divisors (37049472).

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

21427128 is a wasteful number, since it uses less digits than its factorization.

21427128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2292 (or 2285 counting only the distinct ones).

The product of its digits is 1792, while the sum is 27.

The square root of 21427128 is about 4628.9445881324. The cubic root of 21427128 is about 277.7503754421.

The spelling of 21427128 in words is "twenty-one million, four hundred twenty-seven thousand, one hundred twenty-eight".