21453228 has 24 divisors (see below), whose sum is σ = 55619760. Its totient is φ = 7151040.

The previous prime is 21453203. The next prime is 21453239. The reversal of 21453228 is 82235412.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 99213 + ... + 99428.

It is an arithmetic number, because the mean of its divisors is an integer number (2317490).

Almost surely, 2^21453228 is an apocalyptic number.

It is an amenable number.

21453228 is an abundant number, since it is smaller than the sum of its proper divisors (34166532).

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

21453228 is a wasteful number, since it uses less digits than its factorization.

21453228 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 198654 (or 198646 counting only the distinct ones).

The product of its digits is 3840, while the sum is 27.

The square root of 21453228 is about 4631.7629473020. The cubic root of 21453228 is about 277.8631039325.

The spelling of 21453228 in words is "twenty-one million, four hundred fifty-three thousand, two hundred twenty-eight".