21317984500 has 48 divisors (see below), whose sum is σ = 46993722048. Its totient is φ = 8447479200.

The previous prime is 21317984473. The next prime is 21317984509. The reversal of 21317984500 is 548971312.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21317984509) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 145734 + ... + 252733.

It is an arithmetic number, because the mean of its divisors is an integer number (979035876).

Almost surely, 2^21317984500 is an apocalyptic number.

21317984500 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21317984500 is an abundant number, since it is smaller than the sum of its proper divisors (25675737548).

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

21317984500 is a wasteful number, since it uses less digits than its factorization.

21317984500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 398593 (or 398581 counting only the distinct ones).

The product of its (nonzero) digits is 60480, while the sum is 40.

The spelling of 21317984500 in words is "twenty-one billion, three hundred seventeen million, nine hundred eighty-four thousand, five hundred".