21180228 has 24 divisors (see below), whose sum is σ = 49543200. Its totient is φ = 7042560.

The previous prime is 21180227. The next prime is 21180239. The reversal of 21180228 is 82208112.

It is a junction number, because it is equal to n+sod(n) for n = 21180198 and 21180207.

It is not an unprimeable number, because it can be changed into a prime (21180227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3423 + ... + 7353.

It is an arithmetic number, because the mean of its divisors is an integer number (2064300).

Almost surely, 2^21180228 is an apocalyptic number.

It is an amenable number.

21180228 is an abundant number, since it is smaller than the sum of its proper divisors (28362972).

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

21180228 is a wasteful number, since it uses less digits than its factorization.

21180228 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4387 (or 4385 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 24.

The square root of 21180228 is about 4602.1981704399. The cubic root of 21180228 is about 276.6794329684.

The spelling of 21180228 in words is "twenty-one million, one hundred eighty thousand, two hundred twenty-eight".