21221360 has 80 divisors (see below), whose sum is σ = 52377600. Its totient is φ = 7983360.

The previous prime is 21221353. The next prime is 21221363. The reversal of 21221360 is 6312212.

It is a tau number, because it is divible by the number of its divisors (80).

It is a super-2 number, since 2×21221360² = 900692240499200, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221363) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 106541 + ... + 106739.

It is an arithmetic number, because the mean of its divisors is an integer number (654720).

Almost surely, 2^21221360 is an apocalyptic number.

21221360 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 21221360, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26188800).

21221360 is an abundant number, since it is smaller than the sum of its proper divisors (31156240).

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

21221360 is a wasteful number, since it uses less digits than its factorization.

21221360 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 286 (or 280 counting only the distinct ones).

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

The square root of 21221360 is about 4606.6647370956. The cubic root of 21221360 is about 276.8584209610.

Adding to 21221360 its reverse (6312212), we get a palindrome (27533572).

The spelling of 21221360 in words is "twenty-one million, two hundred twenty-one thousand, three hundred sixty".