21203255606 has 16 divisors (see below), whose sum is σ = 34980168384. Its totient is φ = 9577902144.

The previous prime is 21203255587. The next prime is 21203255611. The reversal of 21203255606 is 60655230212.

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, 8674415 + ... + 8676858.

It is an arithmetic number, because the mean of its divisors is an integer number (2186260524).

Almost surely, 2^21203255606 is an apocalyptic number.

21203255606 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

21203255606 is a deficient number, since it is larger than the sum of its proper divisors (13776912778).

21203255606 is a wasteful number, since it uses less digits than its factorization.

21203255606 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17351335.

The product of its (nonzero) digits is 21600, while the sum is 32.

Adding to 21203255606 its reverse (60655230212), we get a palindrome (81858485818).

The spelling of 21203255606 in words is "twenty-one billion, two hundred three million, two hundred fifty-five thousand, six hundred six".