21208258 has 16 divisors (see below), whose sum is σ = 32555520. Its totient is φ = 10358800.

The previous prime is 21208183. The next prime is 21208259. The reversal of 21208258 is 85280212.

It is a plaindrome in base 15.

It is not an unprimeable number, because it can be changed into a prime (21208259) 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 7 ways as a sum of consecutive naturals, for example, 22068 + ... + 23008.

It is an arithmetic number, because the mean of its divisors is an integer number (2034720).

Almost surely, 2^21208258 is an apocalyptic number.

21208258 is a deficient number, since it is larger than the sum of its proper divisors (11347262).

21208258 is a wasteful number, since it uses less digits than its factorization.

21208258 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1193.

The product of its (nonzero) digits is 2560, while the sum is 28.

The square root of 21208258 is about 4605.2424474722. The cubic root of 21208258 is about 276.8014320624.

The spelling of 21208258 in words is "twenty-one million, two hundred eight thousand, two hundred fifty-eight".