21212315 has 8 divisors (see below), whose sum is σ = 25813728. Its totient is φ = 16730560.

The previous prime is 21212297. The next prime is 21212353. The reversal of 21212315 is 51321212.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21212315 - 2¹⁶ = 21146779 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21212293 and 21212302.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 29522 + ... + 30231.

It is an arithmetic number, because the mean of its divisors is an integer number (3226716).

Almost surely, 2^21212315 is an apocalyptic number.

21212315 is a deficient number, since it is larger than the sum of its proper divisors (4601413).

21212315 is an equidigital number, since it uses as much as digits as its factorization.

21212315 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 59829.

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

The square root of 21212315 is about 4605.6829026758. The cubic root of 21212315 is about 276.8190810337.

Adding to 21212315 its reverse (51321212), we get a palindrome (72533527).

The spelling of 21212315 in words is "twenty-one million, two hundred twelve thousand, three hundred fifteen".