21208218 has 16 divisors (see below), whose sum is σ = 44649120. Its totient is φ = 6697296.

The previous prime is 21208183. The next prime is 21208259. The reversal of 21208218 is 81280212.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 92905 + ... + 93132.

It is an arithmetic number, because the mean of its divisors is an integer number (2790570).

Almost surely, 2^21208218 is an apocalyptic number.

21208218 is an abundant number, since it is smaller than the sum of its proper divisors (23440902).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21208218 is a wasteful number, since it uses less digits than its factorization.

21208218 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 186061.

The product of its (nonzero) digits is 512, while the sum is 24.

The square root of 21208218 is about 4605.2381045935. The cubic root of 21208218 is about 276.8012580411.

The spelling of 21208218 in words is "twenty-one million, two hundred eight thousand, two hundred eighteen".