21000206 has 16 divisors (see below), whose sum is σ = 34229760. Its totient is φ = 9626040.

The previous prime is 21000193. The next prime is 21000229. The reversal of 21000206 is 60200012.

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, 7736 + ... + 10091.

It is an arithmetic number, because the mean of its divisors is an integer number (2139360).

Almost surely, 2^21000206 is an apocalyptic number.

21000206 is a deficient number, since it is larger than the sum of its proper divisors (13229554).

21000206 is a wasteful number, since it uses less digits than its factorization.

21000206 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17879.

The product of its (nonzero) digits is 24, while the sum is 11.

The square root of 21000206 is about 4582.5981713434. The cubic root of 21000206 is about 275.8933197596.

Adding to 21000206 its reverse (60200012), we get a palindrome (81200218).

The spelling of 21000206 in words is "twenty-one million, two hundred six", and thus it is an aban number.