21031200000 has 648 divisors, whose sum is σ = 79710898176. Its totient is φ = 5322240000.

The previous prime is 21031199999. The next prime is 21031200019. The reversal of 21031200000 is 213012.

It is a happy number.

It is a super-2 number, since 2×21031200000² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 165599937 + ... + 165600063.

Almost surely, 2^21031200000 is an apocalyptic number.

21031200000 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 21031200000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39855449088).

21031200000 is an abundant number, since it is smaller than the sum of its proper divisors (58679698176).

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

21031200000 is an equidigital number, since it uses as much as digits as its factorization.

21031200000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 197 (or 160 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 9.

Adding to 21031200000 its reverse (213012), we get a palindrome (21031413012).

The spelling of 21031200000 in words is "twenty-one billion, thirty-one million, two hundred thousand".