21438900 has 216 divisors, whose sum is σ = 79619904. Its totient is φ = 4723200.

The previous prime is 21438881. The next prime is 21438913. The reversal of 21438900 is 983412.

It is a plaindrome in base 11.

It is a zygodrome in base 11.

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 71 ways as a sum of consecutive naturals, for example, 258259 + ... + 258341.

Almost surely, 2^21438900 is an apocalyptic number.

21438900 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 21438900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39809952).

21438900 is an abundant number, since it is smaller than the sum of its proper divisors (58181004).

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

21438900 is a wasteful number, since it uses less digits than its factorization.

21438900 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 151 (or 141 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 21438900 is about 4630.2159776840. The cubic root of 21438900 is about 277.8012312049.

The spelling of 21438900 in words is "twenty-one million, four hundred thirty-eight thousand, nine hundred".