21424000 has 128 divisors (see below), whose sum is σ = 57919680. Its totient is φ = 7833600.

The previous prime is 21423989. The next prime is 21424003. The reversal of 21424000 is 42412.

It is a tau number, because it is divible by the number of its divisors (128).

It is a Harshad number since it is a multiple of its sum of digits (13).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21424003) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 207949 + ... + 208051.

Almost surely, 2^21424000 is an apocalyptic number.

21424000 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 21424000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28959840).

21424000 is an abundant number, since it is smaller than the sum of its proper divisors (36495680).

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

21424000 is a wasteful number, since it uses less digits than its factorization.

21424000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 145 (or 123 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 13.

The square root of 21424000 is about 4628.6067018056. The cubic root of 21424000 is about 277.7368591579.

Adding to 21424000 its reverse (42412), we get a palindrome (21466412).

The spelling of 21424000 in words is "twenty-one million, four hundred twenty-four thousand".