21864628 has 18 divisors (see below), whose sum is σ = 40002914. Its totient is φ = 10455984.

The previous prime is 21864617. The next prime is 21864653. The reversal of 21864628 is 82646812.

It can be written as a sum of positive squares in only one way, i.e., 20322064 + 1542564 = 4508^2 + 1242^2 .

It is a congruent number.

It is an unprimeable number.

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 5 ways as a sum of consecutive naturals, for example, 3051 + ... + 7282.

Almost surely, 2^21864628 is an apocalyptic number.

It is an amenable number.

21864628 is a deficient number, since it is larger than the sum of its proper divisors (18138286).

21864628 is a wasteful number, since it uses less digits than its factorization.

21864628 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10383 (or 10358 counting only the distinct ones).

The product of its digits is 36864, while the sum is 37.

The square root of 21864628 is about 4675.9627885602. The cubic root of 21864628 is about 279.6280264687.

It can be divided in two parts, 218 and 64628, that added together give a palindrome (64846).

The spelling of 21864628 in words is "twenty-one million, eight hundred sixty-four thousand, six hundred twenty-eight".