21071228 has 48 divisors (see below), whose sum is σ = 42094080. Its totient is φ = 9167616.

The previous prime is 21071221. The next prime is 21071249. The reversal of 21071228 is 82217012.

It is a super-3 number, since 3×21071228³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21071221) 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 15 ways as a sum of consecutive naturals, for example, 60551 + ... + 60897.

It is an arithmetic number, because the mean of its divisors is an integer number (876960).

Almost surely, 2^21071228 is an apocalyptic number.

It is an amenable number.

21071228 is a deficient number, since it is larger than the sum of its proper divisors (21022852).

21071228 is a wasteful number, since it uses less digits than its factorization.

21071228 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 434 (or 432 counting only the distinct ones).

The product of its (nonzero) digits is 448, while the sum is 23.

The square root of 21071228 is about 4590.3407280942. The cubic root of 21071228 is about 276.2039904812.

The spelling of 21071228 in words is "twenty-one million, seventy-one thousand, two hundred twenty-eight".