21543731500 has 96 divisors (see below), whose sum is σ = 48046654656. Its totient is φ = 8435980800.

The previous prime is 21543731479. The next prime is 21543731507. The reversal of 21543731500 is 513734512.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21543731507) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 20854984 + ... + 20856016.

It is an arithmetic number, because the mean of its divisors is an integer number (500485986).

Almost surely, 2^21543731500 is an apocalyptic number.

21543731500 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21543731500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24023327328).

21543731500 is an abundant number, since it is smaller than the sum of its proper divisors (26502923156).

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

21543731500 is a wasteful number, since it uses less digits than its factorization.

21543731500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1892 (or 1880 counting only the distinct ones).

The product of its (nonzero) digits is 12600, while the sum is 31.

The spelling of 21543731500 in words is "twenty-one billion, five hundred forty-three million, seven hundred thirty-one thousand, five hundred".