21230028 has 36 divisors (see below), whose sum is σ = 53916408. Its totient is φ = 7043520.

The previous prime is 21230023. The next prime is 21230047. The reversal of 21230028 is 82003212.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (36).

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

It is not an unprimeable number, because it can be changed into a prime (21230023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 7123 + ... + 9653.

It is an arithmetic number, because the mean of its divisors is an integer number (1497678).

Almost surely, 2^21230028 is an apocalyptic number.

It is an amenable number.

21230028 is an abundant number, since it is smaller than the sum of its proper divisors (32686380).

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

21230028 is a wasteful number, since it uses less digits than its factorization.

21230028 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2774 (or 2769 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 21230028 is about 4607.6054518589. The cubic root of 21230028 is about 276.8961106933.

The spelling of 21230028 in words is "twenty-one million, two hundred thirty thousand, twenty-eight".