21031800000 has 168 divisors, whose sum is σ = 69555829392. Its totient is φ = 5608320000.

The previous prime is 21031799993. The next prime is 21031800037. The reversal of 21031800000 is 813012.

It is a happy number.

It is a super-2 number, since 2×21031800000² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 582474 + ... + 617526.

It is an arithmetic number, because the mean of its divisors is an integer number (414022794).

Almost surely, 2^21031800000 is an apocalyptic number.

21031800000 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 21031800000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34777914696).

21031800000 is an abundant number, since it is smaller than the sum of its proper divisors (48524029392).

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

21031800000 is an frugal number, since it uses more digits than its factorization.

21031800000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35093 (or 35063 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 15.

The spelling of 21031800000 in words is "twenty-one billion, thirty-one million, eight hundred thousand".