21536550225 has 144 divisors (see below), whose sum is σ = 40686235200. Its totient is φ = 10878312960.

The previous prime is 21536550223. The next prime is 21536550229. The reversal of 21536550225 is 52205563512.

21536550225 is a `hidden beast` number, since 21 + 5 + 365 + 50 + 225 = 666.

It is not a de Polignac number, because 21536550225 - 2¹ = 21536550223 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21536550225.

It is not an unprimeable number, because it can be changed into a prime (21536550221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 80061391 + ... + 80061659.

It is an arithmetic number, because the mean of its divisors is an integer number (282543300).

Almost surely, 2^21536550225 is an apocalyptic number.

21536550225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21536550225 is a deficient number, since it is larger than the sum of its proper divisors (19149684975).

21536550225 is a wasteful number, since it uses less digits than its factorization.

21536550225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 544 (or 536 counting only the distinct ones).

The product of its (nonzero) digits is 90000, while the sum is 36.

The spelling of 21536550225 in words is "twenty-one billion, five hundred thirty-six million, five hundred fifty thousand, two hundred twenty-five".