21520404351225 has 144 divisors (see below), whose sum is σ = 43265549716480. Its totient is φ = 10153350259200.

The previous prime is 21520404351157. The next prime is 21520404351239. The reversal of 21520404351225 is 52215340402512.

21520404351225 is a `hidden beast` number, since 2 + 1 + 5 + 20 + 404 + 3 + 5 + 1 + 225 = 666.

It is not a de Polignac number, because 21520404351225 - 2¹⁰ = 21520404350201 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21520404351225.

It is an unprimeable number.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 8187411 + ... + 10491639.

Almost surely, 2^{21520404351225} is an apocalyptic number.

21520404351225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21520404351225 is an abundant number, since it is smaller than the sum of its proper divisors (21745145365255).

21520404351225 is a wasteful number, since it uses less digits than its factorization.

21520404351225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2304392 (or 2304384 counting only the distinct ones).

The product of its (nonzero) digits is 96000, while the sum is 36.

Adding to 21520404351225 its reverse (52215340402512), we get a palindrome (73735744753737).

The spelling of 21520404351225 in words is "twenty-one trillion, five hundred twenty billion, four hundred four million, three hundred fifty-one thousand, two hundred twenty-five".