21243135500 has 24 divisors (see below), whose sum is σ = 46395009024. Its totient is φ = 8497254000.

The previous prime is 21243135499. The next prime is 21243135559. The reversal of 21243135500 is 553134212.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21243135500.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21242636 + ... + 21243635.

It is an arithmetic number, because the mean of its divisors is an integer number (1933125376).

Almost surely, 2^21243135500 is an apocalyptic number.

21243135500 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21243135500 is an abundant number, since it is smaller than the sum of its proper divisors (25151873524).

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

21243135500 is a wasteful number, since it uses less digits than its factorization.

21243135500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42486290 (or 42486278 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 26.

Adding to 21243135500 its reverse (553134212), we get a palindrome (21796269712).

The spelling of 21243135500 in words is "twenty-one billion, two hundred forty-three million, one hundred thirty-five thousand, five hundred".