21315600 has 180 divisors, whose sum is σ = 76756992. Its totient is φ = 5472000.

The previous prime is 21315599. The next prime is 21315607. The reversal of 21315600 is 651312.

It is a tau number, because it is divible by the number of its divisors (180).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (21315607) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 111505 + ... + 111695.

Almost surely, 2^21315600 is an apocalyptic number.

21315600 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 21315600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38378496).

21315600 is an abundant number, since it is smaller than the sum of its proper divisors (55441392).

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

21315600 is a wasteful number, since it uses less digits than its factorization.

21315600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 246 (or 232 counting only the distinct ones).

The product of its (nonzero) digits is 180, while the sum is 18.

The square root of 21315600 is about 4616.8820647706. The cubic root of 21315600 is about 277.2676408960.

Adding to 21315600 its reverse (651312), we get a palindrome (21966912).

The spelling of 21315600 in words is "twenty-one million, three hundred fifteen thousand, six hundred".