21321600 has 96 divisors (see below), whose sum is σ = 70259640. Its totient is φ = 5683200.

The previous prime is 21321589. The next prime is 21321617. The reversal of 21321600 is 612312.

It is a tau number, because it is divible by the number of its divisors (96).

It is a super-2 number, since 2×21321600² = 909221253120000, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21321600.

It is a congruent number.

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, 8490 + ... + 10710.

Almost surely, 2^21321600 is an apocalyptic number.

21321600 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 21321600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35129820).

21321600 is an abundant number, since it is smaller than the sum of its proper divisors (48938040).

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

21321600 is a wasteful number, since it uses less digits than its factorization.

21321600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2248 (or 2231 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 15.

The square root of 21321600 is about 4617.5318082283. The cubic root of 21321600 is about 277.2936539221.

Adding to 21321600 its reverse (612312), we get a palindrome (21933912).

The spelling of 21321600 in words is "twenty-one million, three hundred twenty-one thousand, six hundred".