21265906554 has 24 divisors (see below), whose sum is σ = 46079560800. Its totient is φ = 7088107848.

The previous prime is 21265906549. The next prime is 21265906573. The reversal of 21265906554 is 45560956212.

21265906554 is a `hidden beast` number, since 2 + 1 + 2 + 6 + 5 + 90 + 6 + 554 = 666.

It is a Curzon number.

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 262147 + ... + 333545.

It is an arithmetic number, because the mean of its divisors is an integer number (1919981700).

Almost surely, 2^21265906554 is an apocalyptic number.

21265906554 is an abundant number, since it is smaller than the sum of its proper divisors (24813654246).

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

21265906554 is a wasteful number, since it uses less digits than its factorization.

21265906554 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87954 (or 87951 counting only the distinct ones).

The product of its (nonzero) digits is 648000, while the sum is 45.

The spelling of 21265906554 in words is "twenty-one billion, two hundred sixty-five million, nine hundred six thousand, five hundred fifty-four".