21155244205 has 16 divisors (see below), whose sum is σ = 25564089600. Its totient is φ = 16805750400.

The previous prime is 21155244101. The next prime is 21155244211. The reversal of 21155244205 is 50244255112.

It is not a de Polignac number, because 21155244205 - 2⁹ = 21155243693 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, 3748776 + ... + 3754414.

It is an arithmetic number, because the mean of its divisors is an integer number (1597755600).

Almost surely, 2^21155244205 is an apocalyptic number.

It is an amenable number.

21155244205 is a deficient number, since it is larger than the sum of its proper divisors (4408845395).

21155244205 is a wasteful number, since it uses less digits than its factorization.

21155244205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10764.

The product of its (nonzero) digits is 16000, while the sum is 31.

Adding to 21155244205 its reverse (50244255112), we get a palindrome (71399499317).

The spelling of 21155244205 in words is "twenty-one billion, one hundred fifty-five million, two hundred forty-four thousand, two hundred five".