21500012424 has 128 divisors (see below), whose sum is σ = 59512320000. Its totient is φ = 6418214400.

The previous prime is 21500012423. The next prime is 21500012437. The reversal of 21500012424 is 42421000512.

It is a self number, because there is not a number n which added to its sum of digits gives 21500012424.

It is not an unprimeable number, because it can be changed into a prime (21500012423) 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, 12491884 + ... + 12493604.

It is an arithmetic number, because the mean of its divisors is an integer number (464940000).

Almost surely, 2^21500012424 is an apocalyptic number.

21500012424 is a gapful number since it is divisible by the number (24) 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 21500012424, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29756160000).

21500012424 is an abundant number, since it is smaller than the sum of its proper divisors (38012307576).

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

21500012424 is a wasteful number, since it uses less digits than its factorization.

21500012424 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2419 (or 2415 counting only the distinct ones).

The product of its (nonzero) digits is 640, while the sum is 21.

Adding to 21500012424 its reverse (42421000512), we get a palindrome (63921012936).

The spelling of 21500012424 in words is "twenty-one billion, five hundred million, twelve thousand, four hundred twenty-four".