21000010000 has 50 divisors (see below), whose sum is σ = 50843148422. Its totient is φ = 8400000000.

The previous prime is 21000009997. The next prime is 21000010001. The reversal of 21000010000 is 1000012.

It can be written as a sum of positive squares in 5 ways, for example, as 1805570064 + 19194439936 = 42492^2 + 138544^2 .

It is a tau number, because it is divible by the number of its divisors (50).

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

It is not an unprimeable number, because it can be changed into a prime (21000010001) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 1040001 + ... + 1060000.

Almost surely, 2^21000010000 is an apocalyptic number.

21000010000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21000010000 is an abundant number, since it is smaller than the sum of its proper divisors (29843138422).

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

21000010000 is an equidigital number, since it uses as much as digits as its factorization.

21000010000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2100029 (or 2100008 counting only the distinct ones).

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

Adding to 21000010000 its reverse (1000012), we get a palindrome (21001010012).

The spelling of 21000010000 in words is "twenty-one billion, ten thousand".