21142800 has 180 divisors, whose sum is σ = 83952960. Its totient is φ = 4826880.

The previous prime is 21142789. The next prime is 21142811. The reversal of 21142800 is 824112.

It is an interprime number because it is at equal distance from previous prime (21142789) and next prime (21142811).

It is a tau number, because it is divible by the number of its divisors (180).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 24781 + ... + 25619.

Almost surely, 2^21142800 is an apocalyptic number.

21142800 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 21142800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41976480).

21142800 is an abundant number, since it is smaller than the sum of its proper divisors (62810160).

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

21142800 is a wasteful number, since it uses less digits than its factorization.

21142800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 870 (or 856 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

The square root of 21142800 is about 4598.1300547070. The cubic root of 21142800 is about 276.5163616416.

Adding to 21142800 its reverse (824112), we get a palindrome (21966912).

The spelling of 21142800 in words is "twenty-one million, one hundred forty-two thousand, eight hundred".