21423055556 has 24 divisors (see below), whose sum is σ = 42855919680. Its totient is φ = 9179207712.

The previous prime is 21423055519. The next prime is 21423055573. The reversal of 21423055556 is 65555032412.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 40190 + ... + 210858.

It is an arithmetic number, because the mean of its divisors is an integer number (1785663320).

Almost surely, 2^21423055556 is an apocalyptic number.

It is an amenable number.

21423055556 is an abundant number, since it is smaller than the sum of its proper divisors (21432864124).

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

21423055556 is a wasteful number, since it uses less digits than its factorization.

21423055556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 175163 (or 175161 counting only the distinct ones).

The product of its (nonzero) digits is 180000, while the sum is 38.

Adding to 21423055556 its reverse (65555032412), we get a palindrome (86978087968).

The spelling of 21423055556 in words is "twenty-one billion, four hundred twenty-three million, fifty-five thousand, five hundred fifty-six".