21258328 has 32 divisors (see below), whose sum is σ = 49059360. Its totient is φ = 8409600.

The previous prime is 21258301. The next prime is 21258329. The reversal of 21258328 is 82385212.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors.

It is a zygodrome in base 3.

It is a self number, because there is not a number n which added to its sum of digits gives 21258328.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21258329) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13873 + ... + 15328.

It is an arithmetic number, because the mean of its divisors is an integer number (1533105).

Almost surely, 2^21258328 is an apocalyptic number.

21258328 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21258328 is an abundant number, since it is smaller than the sum of its proper divisors (27801032).

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

21258328 is a wasteful number, since it uses less digits than its factorization.

21258328 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29227 (or 29223 counting only the distinct ones).

The product of its digits is 7680, while the sum is 31.

The square root of 21258328 is about 4610.6754385881. The cubic root of 21258328 is about 277.0190918562.

The spelling of 21258328 in words is "twenty-one million, two hundred fifty-eight thousand, three hundred twenty-eight".