21230100 has 90 divisors (see below), whose sum is σ = 68845854. Its totient is φ = 5659200.

The previous prime is 21230047. The next prime is 21230123. The reversal of 21230100 is 103212.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 3640464 + 17589636 = 1908^2 + 4194^2 .

It is a tau number, because it is divible by the number of its divisors (90).

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 6790 + ... + 9410.

Almost surely, 2^21230100 is an apocalyptic number.

21230100 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 21230100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34422927).

21230100 is an abundant number, since it is smaller than the sum of its proper divisors (47615754).

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

21230100 is a wasteful number, since it uses less digits than its factorization.

21230100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2647 (or 2631 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 9.

The square root of 21230100 is about 4607.6132650213. The cubic root of 21230100 is about 276.8964237168.

Adding to 21230100 its reverse (103212), we get a palindrome (21333312).

The spelling of 21230100 in words is "twenty-one million, two hundred thirty thousand, one hundred".