21344400 has 405 divisors, whose sum is σ = 94709433. Its totient is φ = 4435200.

The previous prime is 21344369. The next prime is 21344417. The reversal of 21344400 is 444312.

21344400 = 106² + 107² + ... + 402².

The square root of 21344400 is 4620.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 7683984 + 13660416 = 2772^2 + 3696^2 .

It is a super-2 number, since 2×21344400² = 911166822720000, which contains 22 as substring.

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 80 ways as a sum of consecutive naturals, for example, 1940395 + ... + 1940405.

Almost surely, 2^21344400 is an apocalyptic number.

21344400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

21344400 is the 4620-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21344400

21344400 is an abundant number, since it is smaller than the sum of its proper divisors (73365033).

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

21344400 is a wasteful number, since it uses less digits than its factorization.

21344400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60 (or 28 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 18.

The cubic root of 21344400 is about 277.3924589381.

Adding to 21344400 its reverse (444312), we get a palindrome (21788712).

The spelling of 21344400 in words is "twenty-one million, three hundred forty-four thousand, four hundred".