21213286 has 8 divisors (see below), whose sum is σ = 31839480. Its totient is φ = 10600128.

The previous prime is 21213251. The next prime is 21213287. The reversal of 21213286 is 68231212.

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

It is a self number, because there is not a number n which added to its sum of digits gives 21213286.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21213287) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 4665 + ... + 8011.

It is an arithmetic number, because the mean of its divisors is an integer number (3979935).

Almost surely, 2^21213286 is an apocalyptic number.

21213286 is a deficient number, since it is larger than the sum of its proper divisors (10626194).

21213286 is a wasteful number, since it uses less digits than its factorization.

21213286 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6518.

The product of its digits is 1152, while the sum is 25.

The square root of 21213286 is about 4605.7883147188. The cubic root of 21213286 is about 276.8233047944.

Adding to 21213286 its reverse (68231212), we get a palindrome (89444498).

The spelling of 21213286 in words is "twenty-one million, two hundred thirteen thousand, two hundred eighty-six".