21428056 has 16 divisors (see below), whose sum is σ = 43268400. Its totient is φ = 9889824.

The previous prime is 21428051. The next prime is 21428081. The reversal of 21428056 is 65082412.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21428051) 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, 102916 + ... + 103123.

It is an arithmetic number, because the mean of its divisors is an integer number (2704275).

Almost surely, 2^21428056 is an apocalyptic number.

21428056 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

21428056 is an abundant number, since it is smaller than the sum of its proper divisors (21840344).

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

21428056 is a wasteful number, since it uses less digits than its factorization.

21428056 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 206058 (or 206054 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 28.

The square root of 21428056 is about 4629.0448258793. The cubic root of 21428056 is about 277.7543851353.

The spelling of 21428056 in words is "twenty-one million, four hundred twenty-eight thousand, fifty-six".