21000010000000 has 128 divisors (see below), whose sum is σ = 52294837804560. Its totient is φ = 8400000000000.

The previous prime is 21000009999967. The next prime is 21000010000019. The reversal of 21000010000000 is 1000012.

It can be written as a sum of positive squares in 8 ways, for example, as 12949806805056 + 8050203194944 = 3598584^2 + 2837288^2 .

It is a tau number, because it is divible by the number of its divisors (128).

It is a Harshad number since it is a multiple of its sum of digits (4).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8950000 + ... + 11050000.

Almost surely, 2^{21000010000000} is an apocalyptic number.

21000010000000 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 21000010000000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26147418902280).

21000010000000 is an abundant number, since it is smaller than the sum of its proper divisors (31294827804560).

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

21000010000000 is an frugal number, since it uses more digits than its factorization.

21000010000000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2100050 (or 2100008 counting only the distinct ones).

The product of its (nonzero) digits is 2, while the sum is 4.

Adding to 21000010000000 its reverse (1000012), we get a palindrome (21000011000012).

The spelling of 21000010000000 in words is "twenty-one trillion, ten million", and thus it is an aban number and an uban number.