21621454175550 has 24 divisors (see below), whose sum is σ = 53621206355736. Its totient is φ = 5765721113440.

The previous prime is 21621454175513. The next prime is 21621454175611. The reversal of 21621454175550 is 5557145412612.

It is a self number, because there is not a number n which added to its sum of digits gives 21621454175550.

It is a congruent 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, 72071513769 + ... + 72071514068.

It is an arithmetic number, because the mean of its divisors is an integer number (2234216931489).

Almost surely, 2^{21621454175550} is an apocalyptic number.

21621454175550 is an abundant number, since it is smaller than the sum of its proper divisors (31999752180186).

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

21621454175550 is a wasteful number, since it uses less digits than its factorization.

21621454175550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 144143027852 (or 144143027847 counting only the distinct ones).

The product of its (nonzero) digits is 1680000, while the sum is 48.

The spelling of 21621454175550 in words is "twenty-one trillion, six hundred twenty-one billion, four hundred fifty-four million, one hundred seventy-five thousand, five hundred fifty".