21520404104 has 32 divisors (see below), whose sum is σ = 42041721600. Its totient is φ = 10315767360.

The previous prime is 21520404067. The next prime is 21520404107. The reversal of 21520404104 is 40140402512.

It is a self number, because there is not a number n which added to its sum of digits gives 21520404104.

It is not an unprimeable number, because it can be changed into a prime (21520404107) 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, 378959 + ... + 432030.

It is an arithmetic number, because the mean of its divisors is an integer number (1313803800).

Almost surely, 2^21520404104 is an apocalyptic number.

It is an amenable number.

21520404104 is a deficient number, since it is larger than the sum of its proper divisors (20521317496).

21520404104 is a wasteful number, since it uses less digits than its factorization.

21520404104 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 811133 (or 811129 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 23.

Adding to 21520404104 its reverse (40140402512), we get a palindrome (61660806616).

The spelling of 21520404104 in words is "twenty-one billion, five hundred twenty million, four hundred four thousand, one hundred four".