21730020206 has 16 divisors (see below), whose sum is σ = 34362662400. Its totient is φ = 10277536248.

The previous prime is 21730020181. The next prime is 21730020209. The reversal of 21730020206 is 60202003712.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21730020209) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 408830 + ... + 458913.

It is an arithmetic number, because the mean of its divisors is an integer number (2147666400).

Almost surely, 2^21730020206 is an apocalyptic number.

21730020206 is a deficient number, since it is larger than the sum of its proper divisors (12632642194).

21730020206 is a wasteful number, since it uses less digits than its factorization.

21730020206 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 868423.

The product of its (nonzero) digits is 1008, while the sum is 23.

Adding to 21730020206 its reverse (60202003712), we get a palindrome (81932023918).

The spelling of 21730020206 in words is "twenty-one billion, seven hundred thirty million, twenty thousand, two hundred six".