21312543500 has 48 divisors (see below), whose sum is σ = 46783088352. Its totient is φ = 8481704000.

The previous prime is 21312543491. The next prime is 21312543517. The reversal of 21312543500 is 534521312.

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 21312543500.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9686 + ... + 206685.

It is an arithmetic number, because the mean of its divisors is an integer number (974647674).

Almost surely, 2^21312543500 is an apocalyptic number.

21312543500 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21312543500 is an abundant number, since it is smaller than the sum of its proper divisors (25470544852).

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

21312543500 is a wasteful number, since it uses less digits than its factorization.

21312543500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 216587 (or 216575 counting only the distinct ones).

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

The spelling of 21312543500 in words is "twenty-one billion, three hundred twelve million, five hundred forty-three thousand, five hundred".