21435145521 has 32 divisors (see below), whose sum is σ = 31361126400. Its totient is φ = 12962396160.

The previous prime is 21435145493. The next prime is 21435145531. The reversal of 21435145521 is 12554153412.

It is not a de Polignac number, because 21435145521 - 2¹⁸ = 21434883377 is a prime.

It is a super-2 number, since 2×21435145521² (a number of 21 digits) contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21435145531) 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 31 ways as a sum of consecutive naturals, for example, 828816 + ... + 854286.

It is an arithmetic number, because the mean of its divisors is an integer number (980035200).

Almost surely, 2^21435145521 is an apocalyptic number.

It is an amenable number.

21435145521 is a deficient number, since it is larger than the sum of its proper divisors (9925980879).

21435145521 is a wasteful number, since it uses less digits than its factorization.

21435145521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26089.

The product of its digits is 24000, while the sum is 33.

Adding to 21435145521 its reverse (12554153412), we get a palindrome (33989298933).

The spelling of 21435145521 in words is "twenty-one billion, four hundred thirty-five million, one hundred forty-five thousand, five hundred twenty-one".