21428400 has 120 divisors (see below), whose sum is σ = 78479104. Its totient is φ = 4896000.

The previous prime is 21428389. The next prime is 21428401. The reversal of 21428400 is 482412.

It is a tau number, because it is divible by the number of its divisors (120).

It is a Harshad number since it is a multiple of its sum of digits (21).

It is not an unprimeable number, because it can be changed into a prime (21428401) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7125 + ... + 9675.

Almost surely, 2^21428400 is an apocalyptic number.

21428400 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 21428400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39239552).

21428400 is an abundant number, since it is smaller than the sum of its proper divisors (57050704).

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

21428400 is a wasteful number, since it uses less digits than its factorization.

21428400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2579 (or 2568 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 21.

The square root of 21428400 is about 4629.0819824237. The cubic root of 21428400 is about 277.7558714576.

The spelling of 21428400 in words is "twenty-one million, four hundred twenty-eight thousand, four hundred".