21021020206 has 32 divisors (see below), whose sum is σ = 32689115136. Its totient is φ = 10127700000.

The previous prime is 21021020161. The next prime is 21021020239. The reversal of 21021020206 is 60202012012.

It is a self number, because there is not a number n which added to its sum of digits gives 21021020206.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27990331 + ... + 27991081.

It is an arithmetic number, because the mean of its divisors is an integer number (1021534848).

Almost surely, 2^21021020206 is an apocalyptic number.

21021020206 is a deficient number, since it is larger than the sum of its proper divisors (11668094930).

21021020206 is a wasteful number, since it uses less digits than its factorization.

21021020206 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2128.

The product of its (nonzero) digits is 96, while the sum is 16.

Adding to 21021020206 its reverse (60202012012), we get a palindrome (81223032218).

The spelling of 21021020206 in words is "twenty-one billion, twenty-one million, twenty thousand, two hundred six".