21286628 has 12 divisors (see below), whose sum is σ = 40638192. Its totient is φ = 9675720.

The previous prime is 21286627. The next prime is 21286633. The reversal of 21286628 is 82668212.

It is a super-2 number, since 2×21286628² = 906241063220768, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21286627) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 241850 + ... + 241937.

It is an arithmetic number, because the mean of its divisors is an integer number (3386516).

Almost surely, 2^21286628 is an apocalyptic number.

It is an amenable number.

21286628 is a deficient number, since it is larger than the sum of its proper divisors (19351564).

21286628 is a wasteful number, since it uses less digits than its factorization.

21286628 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 483802 (or 483800 counting only the distinct ones).

The product of its digits is 18432, while the sum is 35.

The square root of 21286628 is about 4613.7433825474. The cubic root of 21286628 is about 277.1419639222.

The spelling of 21286628 in words is "twenty-one million, two hundred eighty-six thousand, six hundred twenty-eight".