21008086 has 32 divisors (see below), whose sum is σ = 35463168. Its totient is φ = 9253440.

The previous prime is 21008083. The next prime is 21008149. The reversal of 21008086 is 68080012.

It is a self number, because there is not a number n which added to its sum of digits gives 21008086.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21008081) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 165355 + ... + 165481.

It is an arithmetic number, because the mean of its divisors is an integer number (1108224).

Almost surely, 2^21008086 is an apocalyptic number.

21008086 is a deficient number, since it is larger than the sum of its proper divisors (14455082).

21008086 is a wasteful number, since it uses less digits than its factorization.

21008086 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 316.

The product of its (nonzero) digits is 768, while the sum is 25.

The square root of 21008086 is about 4583.4578649749. The cubic root of 21008086 is about 275.9278236670.

Adding to 21008086 its reverse (68080012), we get a palindrome (89088098).

The spelling of 21008086 in words is "twenty-one million, eight thousand, eighty-six".