21808628 has 12 divisors (see below), whose sum is σ = 38418912. Its totient is φ = 10831800.

The previous prime is 21808621. The next prime is 21808681. The reversal of 21808628 is 82680812.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21808621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17450 + ... + 18657.

It is an arithmetic number, because the mean of its divisors is an integer number (3201576).

Almost surely, 2^21808628 is an apocalyptic number.

It is an amenable number.

21808628 is a deficient number, since it is larger than the sum of its proper divisors (16610284).

21808628 is a wasteful number, since it uses less digits than its factorization.

21808628 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36262 (or 36260 counting only the distinct ones).

The product of its (nonzero) digits is 12288, while the sum is 35.

The square root of 21808628 is about 4669.9708778535. The cubic root of 21808628 is about 279.3890932571.

The spelling of 21808628 in words is "twenty-one million, eight hundred eight thousand, six hundred twenty-eight".