21136400 has 60 divisors (see below), whose sum is σ = 51790212. Its totient is φ = 8286720.

The previous prime is 21136393. The next prime is 21136403. The reversal of 21136400 is 463112.

It can be written as a sum of positive squares in 6 ways, for example, as 633616 + 20502784 = 796^2 + 4528^2 .

It is not an unprimeable number, because it can be changed into a prime (21136403) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 20702 + ... + 21698.

Almost surely, 2^21136400 is an apocalyptic number.

21136400 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 21136400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25895106).

21136400 is an abundant number, since it is smaller than the sum of its proper divisors (30653812).

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

21136400 is a wasteful number, since it uses less digits than its factorization.

21136400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1068 (or 1057 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 17.

The square root of 21136400 is about 4597.4340669552. The cubic root of 21136400 is about 276.4884580005.

Adding to 21136400 its reverse (463112), we get a palindrome (21599512).

The spelling of 21136400 in words is "twenty-one million, one hundred thirty-six thousand, four hundred".