21012000000 has 504 divisors, whose sum is σ = 74732793408. Its totient is φ = 5222400000.

The previous prime is 21011999999. The next prime is 21012000049. The reversal of 21012000000 is 21012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (6).

It is a super Niven number, because it is divisible the sum of any subset of its (nonzero) digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 55 ways as a sum of consecutive naturals, for example, 203999949 + ... + 204000051.

It is an arithmetic number, because the mean of its divisors is an integer number (148279352).

Almost surely, 2^21012000000 is an apocalyptic number.

21012000000 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 21012000000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37366396704).

21012000000 is an abundant number, since it is smaller than the sum of its proper divisors (53720793408).

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

21012000000 is an frugal number, since it uses more digits than its factorization.

21012000000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 169 (or 130 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 6.

Adding to 21012000000 its reverse (21012), we get a palindrome (21012021012).

Multiplying 21012000000 by its reverse (21012), we get a square (441504144000000 = 21012000²).

21012000000 divided by its reverse (21012) gives a 6-th power (1000000 = 10⁶).

The spelling of 21012000000 in words is "twenty-one billion, twelve million", and thus it is an aban number and an uban number.