21651200 has 108 divisors (see below), whose sum is σ = 57027600. Its totient is φ = 8110080.

The previous prime is 21651181. The next prime is 21651209. The reversal of 21651200 is 215612.

It is a super-2 number, since 2×21651200² = 937548922880000, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (17).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21651209) 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, 108701 + ... + 108899.

Almost surely, 2^21651200 is an apocalyptic number.

21651200 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 21651200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28513800).

21651200 is an abundant number, since it is smaller than the sum of its proper divisors (35376400).

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

21651200 is a wasteful number, since it uses less digits than its factorization.

21651200 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 242 (or 223 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 17.

The square root of 21651200 is about 4653.0849981491. The cubic root of 21651200 is about 278.7152020750.

Adding to 21651200 its reverse (215612), we get a palindrome (21866812).

The spelling of 21651200 in words is "twenty-one million, six hundred fifty-one thousand, two hundred".