21601338205 has 16 divisors (see below), whose sum is σ = 26190318960. Its totient is φ = 17102389248.

The previous prime is 21601338173. The next prime is 21601338223. The reversal of 21601338205 is 50283310612.

It can be written as a sum of positive squares in 8 ways, for example, as 12346320996 + 9255017209 = 111114^2 + 96203^2 .

It is a cyclic number.

It is not a de Polignac number, because 21601338205 - 2⁵ = 21601338173 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 351841 + ... + 408649.

It is an arithmetic number, because the mean of its divisors is an integer number (1636894935).

Almost surely, 2^21601338205 is an apocalyptic number.

It is an amenable number.

21601338205 is a deficient number, since it is larger than the sum of its proper divisors (4588980755).

21601338205 is a wasteful number, since it uses less digits than its factorization.

21601338205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57600.

The product of its (nonzero) digits is 8640, while the sum is 31.

Adding to 21601338205 its reverse (50283310612), we get a palindrome (71884648817).

The spelling of 21601338205 in words is "twenty-one billion, six hundred one million, three hundred thirty-eight thousand, two hundred five".