21365228 has 24 divisors (see below), whose sum is σ = 39270000. Its totient is φ = 10156608.

The previous prime is 21365221. The next prime is 21365233. The reversal of 21365228 is 82256312.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a self number, because there is not a number n which added to its sum of digits gives 21365228.

It is not an unprimeable number, because it can be changed into a prime (21365221) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6398 + ... + 9146.

It is an arithmetic number, because the mean of its divisors is an integer number (1636250).

Almost surely, 2^21365228 is an apocalyptic number.

It is an amenable number.

21365228 is a deficient number, since it is larger than the sum of its proper divisors (17904772).

21365228 is a wasteful number, since it uses less digits than its factorization.

21365228 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2849 (or 2847 counting only the distinct ones).

The product of its digits is 5760, while the sum is 29.

The square root of 21365228 is about 4622.2535629279. The cubic root of 21365228 is about 277.4826567090.

The spelling of 21365228 in words is "twenty-one million, three hundred sixty-five thousand, two hundred twenty-eight".