21224228 has 12 divisors (see below), whose sum is σ = 39327372. Its totient is φ = 9987840.

The previous prime is 21224207. The next prime is 21224249. The reversal of 21224228 is 82242212.

It is an interprime number because it is at equal distance from previous prime (21224207) and next prime (21224249).

It can be written as a sum of positive squares in 2 ways, for example, as 18593344 + 2630884 = 4312^2 + 1622^2 .

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, 155993 + ... + 156128.

It is an arithmetic number, because the mean of its divisors is an integer number (3277281).

Almost surely, 2^21224228 is an apocalyptic number.

It is an amenable number.

21224228 is a deficient number, since it is larger than the sum of its proper divisors (18103144).

21224228 is a wasteful number, since it uses less digits than its factorization.

21224228 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 312142 (or 312140 counting only the distinct ones).

The product of its digits is 1024, while the sum is 23.

The square root of 21224228 is about 4606.9760146977. The cubic root of 21224228 is about 276.8708925806.

The spelling of 21224228 in words is "twenty-one million, two hundred twenty-four thousand, two hundred twenty-eight".