21124400 has 60 divisors (see below), whose sum is σ = 55376664. Its totient is φ = 7680000.

The previous prime is 21124391. The next prime is 21124459. The reversal of 21124400 is 442112.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2000 + ... + 6800.

Almost surely, 2^21124400 is an apocalyptic number.

21124400 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 21124400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27688332).

21124400 is an abundant number, since it is smaller than the sum of its proper divisors (34252264).

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

21124400 is a wasteful number, since it uses less digits than its factorization.

21124400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4830 (or 4819 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 14.

The square root of 21124400 is about 4596.1288058539. The cubic root of 21124400 is about 276.4361234877.

Adding to 21124400 its reverse (442112), we get a palindrome (21566512).

It can be divided in two parts, 21 and 124400, that added together give a palindrome (124421).

The spelling of 21124400 in words is "twenty-one million, one hundred twenty-four thousand, four hundred".