21000421000 has 128 divisors (see below), whose sum is σ = 53648431200. Its totient is φ = 7647436800.

The previous prime is 21000420983. The next prime is 21000421003. The reversal of 21000421000 is 12400012.

It can be written as a sum of positive squares in 16 ways, for example, as 142706916 + 20857714084 = 11946^2 + 144422^2 .

It is a Harshad number since it is a multiple of its sum of digits (10).

It is not an unprimeable number, because it can be changed into a prime (21000421003) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 937936 + ... + 960064.

Almost surely, 2^21000421000 is an apocalyptic number.

21000421000 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 21000421000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26824215600).

21000421000 is an abundant number, since it is smaller than the sum of its proper divisors (32648010200).

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

21000421000 is a wasteful number, since it uses less digits than its factorization.

21000421000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22236 (or 22222 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 10.

Adding to 21000421000 its reverse (12400012), we get a palindrome (21012821012).

The spelling of 21000421000 in words is "twenty-one billion, four hundred twenty-one thousand".