21211503500 has 192 divisors, whose sum is σ = 54132624000. Its totient is φ = 7175168000.

The previous prime is 21211503479. The next prime is 21211503571. The reversal of 21211503500 is 530511212.

It is a happy number.

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

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 8320226 + ... + 8322774.

It is an arithmetic number, because the mean of its divisors is an integer number (281940750).

Almost surely, 2^21211503500 is an apocalyptic number.

21211503500 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 21211503500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27066312000).

21211503500 is an abundant number, since it is smaller than the sum of its proper divisors (32921120500).

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

21211503500 is a wasteful number, since it uses less digits than its factorization.

21211503500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2685 (or 2673 counting only the distinct ones).

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

The spelling of 21211503500 in words is "twenty-one billion, two hundred eleven million, five hundred three thousand, five hundred".