21025000100 has 72 divisors (see below), whose sum is σ = 49807098600. Its totient is φ = 7656698880.

The previous prime is 21025000091. The next prime is 21025000109. The reversal of 21025000100 is 100052012.

It is an interprime number because it is at equal distance from previous prime (21025000091) and next prime (21025000109).

It can be written as a sum of positive squares in 12 ways, for example, as 13454608036 + 7570392064 = 115994^2 + 87008^2 .

It is not an unprimeable number, because it can be changed into a prime (21025000109) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 15875 + ... + 205674.

Almost surely, 2^21025000100 is an apocalyptic number.

21025000100 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 21025000100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24903549300).

21025000100 is an abundant number, since it is smaller than the sum of its proper divisors (28782098500).

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

21025000100 is a wasteful number, since it uses less digits than its factorization.

21025000100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 221649 (or 221642 counting only the distinct ones).

The product of its (nonzero) digits is 20, while the sum is 11.

Adding to 21025000100 its reverse (100052012), we get a palindrome (21125052112).

The spelling of 21025000100 in words is "twenty-one billion, twenty-five million, one hundred", and thus it is an aban number.