21011500000 has 84 divisors (see below), whose sum is σ = 51708556872. Its totient is φ = 8404400000.

The previous prime is 21011499997. The next prime is 21011500019. The reversal of 21011500000 is 511012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a self number, because there is not a number n which added to its sum of digits gives 21011500000.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 13 ways as a sum of consecutive naturals, for example, 478989 + ... + 521011.

It is an arithmetic number, because the mean of its divisors is an integer number (615578058).

Almost surely, 2^21011500000 is an apocalyptic number.

21011500000 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 21011500000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25854278436).

21011500000 is an abundant number, since it is smaller than the sum of its proper divisors (30697056872).

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

21011500000 is an frugal number, since it uses more digits than its factorization.

21011500000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42063 (or 42030 counting only the distinct ones).

The product of its (nonzero) digits is 10, while the sum is 10.

The spelling of 21011500000 in words is "twenty-one billion, eleven million, five hundred thousand".