21212360 has 96 divisors (see below), whose sum is σ = 54726840. Its totient is φ = 7354368.

The previous prime is 21212353. The next prime is 21212423. The reversal of 21212360 is 6321212.

It can be written as a sum of positive squares in 4 ways, for example, as 6482116 + 14730244 = 2546^2 + 3838^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 187664 + ... + 187776.

Almost surely, 2^21212360 is an apocalyptic number.

21212360 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 21212360, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27363420).

21212360 is an abundant number, since it is smaller than the sum of its proper divisors (33514480).

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

21212360 is a wasteful number, since it uses less digits than its factorization.

21212360 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 175 (or 152 counting only the distinct ones).

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

The square root of 21212360 is about 4605.6877879422. The cubic root of 21212360 is about 276.8192767824.

Adding to 21212360 its reverse (6321212), we get a palindrome (27533572).

The spelling of 21212360 in words is "twenty-one million, two hundred twelve thousand, three hundred sixty".