21013206 has 16 divisors (see below), whose sum is σ = 42240000. Its totient is φ = 6968808.

The previous prime is 21013189. The next prime is 21013217. The reversal of 21013206 is 60231012.

It is a congruent number.

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, 7606 + ... + 9993.

It is an arithmetic number, because the mean of its divisors is an integer number (2640000).

Almost surely, 2^21013206 is an apocalyptic number.

21013206 is an abundant number, since it is smaller than the sum of its proper divisors (21226794).

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

21013206 is a wasteful number, since it uses less digits than its factorization.

21013206 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17803.

The product of its (nonzero) digits is 72, while the sum is 15.

The square root of 21013206 is about 4584.0163612273. The cubic root of 21013206 is about 275.9502378254.

Adding to 21013206 its reverse (60231012), we get a palindrome (81244218).

The spelling of 21013206 in words is "twenty-one million, thirteen thousand, two hundred six".