21500523421000 has 128 divisors (see below), whose sum is σ = 54185197248000. Its totient is φ = 7938086572800.

The previous prime is 21500523420997. The next prime is 21500523421001. The reversal of 21500523421000 is 12432500512.

It is a Harshad number since it is a multiple of its sum of digits (25).

It is not an unprimeable number, because it can be changed into a prime (21500523421001) 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, 210327901 + ... + 210430099.

It is an arithmetic number, because the mean of its divisors is an integer number (423321853500).

Almost surely, 2^{21500523421000} is an apocalyptic number.

21500523421000 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 21500523421000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27092598624000).

21500523421000 is an abundant number, since it is smaller than the sum of its proper divisors (32684673827000).

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

21500523421000 is a wasteful number, since it uses less digits than its factorization.

21500523421000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 118416 (or 118402 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 25.

Adding to 21500523421000 its reverse (12432500512), we get a palindrome (21512955921512).

The spelling of 21500523421000 in words is "twenty-one trillion, five hundred billion, five hundred twenty-three million, four hundred twenty-one thousand".