21315208 has 8 divisors (see below), whose sum is σ = 39966030. Its totient is φ = 10657600.

The previous prime is 21315187. The next prime is 21315211. The reversal of 21315208 is 80251312.

It can be written as a sum of positive squares in only one way, i.e., 16016004 + 5299204 = 4002^2 + 2302^2 .

It is a tau number, because it is divible by the number of its divisors (8).

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 as a sum of consecutive naturals, namely, 1332193 + ... + 1332208.

Almost surely, 2^21315208 is an apocalyptic number.

It is an amenable number.

21315208 is a deficient number, since it is larger than the sum of its proper divisors (18650822).

21315208 is a wasteful number, since it uses less digits than its factorization.

21315208 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2664407 (or 2664403 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 22.

The square root of 21315208 is about 4616.8396116824. The cubic root of 21315208 is about 277.2659412084.

The spelling of 21315208 in words is "twenty-one million, three hundred fifteen thousand, two hundred eight".