21205105442104 has 16 divisors (see below), whose sum is σ = 39759748864920. Its totient is φ = 10602505744800.

The previous prime is 21205105442083. The next prime is 21205105442107. The reversal of 21205105442104 is 40124450150212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21205105442107) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3915222 + ... + 7598629.

Almost surely, 2^{21205105442104} is an apocalyptic number.

It is an amenable number.

21205105442104 is a deficient number, since it is larger than the sum of its proper divisors (18554643422816).

21205105442104 is a wasteful number, since it uses less digits than its factorization.

21205105442104 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11744070 (or 11744066 counting only the distinct ones).

The product of its (nonzero) digits is 12800, while the sum is 31.

Adding to 21205105442104 its reverse (40124450150212), we get a palindrome (61329555592316).

The spelling of 21205105442104 in words is "twenty-one trillion, two hundred five billion, one hundred five million, four hundred forty-two thousand, one hundred four".