21254403555 has 96 divisors (see below), whose sum is σ = 45975541248. Its totient is φ = 8824550400.

The previous prime is 21254403517. The next prime is 21254403559. The reversal of 21254403555 is 55530445212.

21254403555 is a `hidden beast` number, since 2 + 12 + 54 + 40 + 3 + 555 = 666.

It is not a de Polignac number, because 21254403555 - 2⁸ = 21254403299 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21254403559) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 4713612 + ... + 4718118.

It is an arithmetic number, because the mean of its divisors is an integer number (478911888).

Almost surely, 2^21254403555 is an apocalyptic number.

21254403555 is an abundant number, since it is smaller than the sum of its proper divisors (24721137693).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21254403555 is a wasteful number, since it uses less digits than its factorization.

21254403555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5897 (or 5894 counting only the distinct ones).

The product of its (nonzero) digits is 120000, while the sum is 36.

Adding to 21254403555 its reverse (55530445212), we get a palindrome (76784848767).

The spelling of 21254403555 in words is "twenty-one billion, two hundred fifty-four million, four hundred three thousand, five hundred fifty-five".