21243550405 has 48 divisors (see below), whose sum is σ = 32461720704. Its totient is φ = 13197045120.

The previous prime is 21243550403. The next prime is 21243550411. The reversal of 21243550405 is 50405534212.

It is not a de Polignac number, because 21243550405 - 2¹ = 21243550403 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21243550403) by changing a digit.

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 47 ways as a sum of consecutive naturals, for example, 776184 + ... + 803086.

It is an arithmetic number, because the mean of its divisors is an integer number (676285848).

Almost surely, 2^21243550405 is an apocalyptic number.

It is an amenable number.

21243550405 is a deficient number, since it is larger than the sum of its proper divisors (11218170299).

21243550405 is a wasteful number, since it uses less digits than its factorization.

21243550405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27226 (or 27219 counting only the distinct ones).

The product of its (nonzero) digits is 24000, while the sum is 31.

The spelling of 21243550405 in words is "twenty-one billion, two hundred forty-three million, five hundred fifty thousand, four hundred five".