21151228 has 12 divisors (see below), whose sum is σ = 42302512. Its totient is φ = 9064800.

The previous prime is 21151219. The next prime is 21151241. The reversal of 21151228 is 82215112.

21151228 is an admirable number.

It is a junction number, because it is equal to n+sod(n) for n = 21151199 and 21151208.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 377673 + ... + 377728.

Almost surely, 2^21151228 is an apocalyptic number.

21151228 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21151228 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21151228 is a wasteful number, since it uses less digits than its factorization.

21151228 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 755412 (or 755410 counting only the distinct ones).

The product of its digits is 320, while the sum is 22.

The square root of 21151228 is about 4599.0464229012. The cubic root of 21151228 is about 276.5530986601.

The spelling of 21151228 in words is "twenty-one million, one hundred fifty-one thousand, two hundred twenty-eight".