21008308 has 12 divisors (see below), whose sum is σ = 36968932. Its totient is φ = 10445760.

The previous prime is 21008293. The next prime is 21008329. The reversal of 21008308 is 80380012.

It can be written as a sum of positive squares in 2 ways, for example, as 1542564 + 19465744 = 1242^2 + 4412^2 .

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 3 ways as a sum of consecutive naturals, for example, 13785 + ... + 15232.

Almost surely, 2^21008308 is an apocalyptic number.

It is an amenable number.

21008308 is a deficient number, since it is larger than the sum of its proper divisors (15960624).

21008308 is a wasteful number, since it uses less digits than its factorization.

21008308 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29202 (or 29200 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 22.

The square root of 21008308 is about 4583.4820824347. The cubic root of 21008308 is about 275.9287956064.

It can be divided in two parts, 21008 and 308, that added together give a square (21316 = 146²).

The spelling of 21008308 in words is "twenty-one million, eight thousand, three hundred eight".