21447400 has 96 divisors (see below), whose sum is σ = 54918360. Its totient is φ = 7741440.

The previous prime is 21447397. The next prime is 21447407. The reversal of 21447400 is 474412.

It can be written as a sum of positive squares in 12 ways, for example, as 1179396 + 20268004 = 1086^2 + 4502^2 .

It is not an unprimeable number, because it can be changed into a prime (21447407) 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 23 ways as a sum of consecutive naturals, for example, 189744 + ... + 189856.

Almost surely, 2^21447400 is an apocalyptic number.

21447400 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 21447400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27459180).

21447400 is an abundant number, since it is smaller than the sum of its proper divisors (33470960).

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

21447400 is a wasteful number, since it uses less digits than its factorization.

21447400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 215 (or 206 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 22.

The square root of 21447400 is about 4631.1337704713. The cubic root of 21447400 is about 277.8379401540.

The spelling of 21447400 in words is "twenty-one million, four hundred forty-seven thousand, four hundred".