21228306 has 32 divisors (see below), whose sum is σ = 47573568. Its totient is φ = 6258240.

The previous prime is 21228289. The next prime is 21228307. The reversal of 21228306 is 60382212.

It is not an unprimeable number, because it can be changed into a prime (21228307) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1905 + ... + 6788.

It is an arithmetic number, because the mean of its divisors is an integer number (1486674).

Almost surely, 2^21228306 is an apocalyptic number.

21228306 is an abundant number, since it is smaller than the sum of its proper divisors (26345262).

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

21228306 is a wasteful number, since it uses less digits than its factorization.

21228306 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8746.

The product of its (nonzero) digits is 1152, while the sum is 24.

The square root of 21228306 is about 4607.4185831114. The cubic root of 21228306 is about 276.8886240020. Note that the first 3 decimals are identical.

The spelling of 21228306 in words is "twenty-one million, two hundred twenty-eight thousand, three hundred six".