21121300000 has 72 divisors (see below), whose sum is σ = 51975118692. Its totient is φ = 8448480000.

The previous prime is 21121299949. The next prime is 21121300003. The reversal of 21121300000 is 312112.

It can be written as a sum of positive squares in 6 ways, for example, as 8631896464 + 12489403536 = 92908^2 + 111756^2 .

It is a super-2 number, since 2×21121300000² (a number of 21 digits) contains 22 as substring.

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 21121300000.

It is not an unprimeable number, because it can be changed into a prime (21121300003) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5607 + ... + 205606.

Almost surely, 2^21121300000 is an apocalyptic number.

21121300000 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 21121300000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25987559346).

21121300000 is an abundant number, since it is smaller than the sum of its proper divisors (30853818692).

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

21121300000 is an frugal number, since it uses more digits than its factorization.

21121300000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 211248 (or 211220 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 10.

Adding to 21121300000 its reverse (312112), we get a palindrome (21121612112).

The spelling of 21121300000 in words is "twenty-one billion, one hundred twenty-one million, three hundred thousand".