21123308 has 6 divisors (see below), whose sum is σ = 36965796. Its totient is φ = 10561652.

The previous prime is 21123301. The next prime is 21123313. The reversal of 21123308 is 80332112.

It is a self number, because there is not a number n which added to its sum of digits gives 21123308.

It is not an unprimeable number, because it can be changed into a prime (21123301) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2640410 + ... + 2640417.

It is an arithmetic number, because the mean of its divisors is an integer number (6160966).

Almost surely, 2^21123308 is an apocalyptic number.

It is an amenable number.

21123308 is a deficient number, since it is larger than the sum of its proper divisors (15842488).

21123308 is a wasteful number, since it uses less digits than its factorization.

21123308 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5280831 (or 5280829 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 20.

The square root of 21123308 is about 4596.0100086923. The cubic root of 21123308 is about 276.4313600632.

The spelling of 21123308 in words is "twenty-one million, one hundred twenty-three thousand, three hundred eight".