21429228 has 12 divisors (see below), whose sum is σ = 50001560. Its totient is φ = 7143072.

The previous prime is 21429209. The next prime is 21429257. The reversal of 21429228 is 82292412.

It is a tau number, because it is divible by the number of its divisors (12).

It is a junction number, because it is equal to n+sod(n) for n = 21429195 and 21429204.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 892873 + ... + 892896.

Almost surely, 2^21429228 is an apocalyptic number.

It is an amenable number.

21429228 is an abundant number, since it is smaller than the sum of its proper divisors (28572332).

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

21429228 is a wasteful number, since it uses less digits than its factorization.

21429228 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1785776 (or 1785774 counting only the distinct ones).

The product of its digits is 4608, while the sum is 30.

The square root of 21429228 is about 4629.1714161392. The cubic root of 21429228 is about 277.7594489358.

The spelling of 21429228 in words is "twenty-one million, four hundred twenty-nine thousand, two hundred twenty-eight".