21512135000 has 80 divisors (see below), whose sum is σ = 51475897440. Its totient is φ = 8421680000.

The previous prime is 21512134997. The next prime is 21512135003. The reversal of 21512135000 is 53121512.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21512134997) and next prime (21512135003).

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21512135003) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 189230 + ... + 280770.

It is an arithmetic number, because the mean of its divisors is an integer number (643448718).

Almost surely, 2^21512135000 is an apocalyptic number.

21512135000 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 21512135000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25737948720).

21512135000 is an abundant number, since it is smaller than the sum of its proper divisors (29963762440).

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

21512135000 is an equidigital number, since it uses as much as digits as its factorization.

21512135000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91614 (or 91595 counting only the distinct ones).

The product of its (nonzero) digits is 300, while the sum is 20.

Adding to 21512135000 its reverse (53121512), we get a palindrome (21565256512).

The spelling of 21512135000 in words is "twenty-one billion, five hundred twelve million, one hundred thirty-five thousand".