21144400 has 30 divisors (see below), whose sum is σ = 50800382. Its totient is φ = 8457600.

The previous prime is 21144373. The next prime is 21144419. The reversal of 21144400 is 444112.

It can be written as a sum of positive squares in 3 ways, for example, as 2274064 + 18870336 = 1508^2 + 4344^2 .

It is a Harshad number since it is a multiple of its sum of digits (16).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 26031 + ... + 26830.

Almost surely, 2^21144400 is an apocalyptic number.

21144400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21144400 is an abundant number, since it is smaller than the sum of its proper divisors (29655982).

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

21144400 is a wasteful number, since it uses less digits than its factorization.

21144400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52879 (or 52868 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 16.

The square root of 21144400 is about 4598.3040351851. The cubic root of 21144400 is about 276.5233366720.

Adding to 21144400 its reverse (444112), we get a palindrome (21588512).

The spelling of 21144400 in words is "twenty-one million, one hundred forty-four thousand, four hundred".