21220385 has 8 divisors (see below), whose sum is σ = 25503360. Its totient is φ = 16950384.

The previous prime is 21220379. The next prime is 21220391. The reversal of 21220385 is 58302212.

It is an interprime number because it is at equal distance from previous prime (21220379) and next prime (21220391).

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

It is a cyclic number.

It is not a de Polignac number, because 21220385 - 2¹⁰ = 21219361 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21220385.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 824 + ... + 6566.

It is an arithmetic number, because the mean of its divisors is an integer number (3187920).

Almost surely, 2^21220385 is an apocalyptic number.

It is an amenable number.

21220385 is a deficient number, since it is larger than the sum of its proper divisors (4282975).

21220385 is an equidigital number, since it uses as much as digits as its factorization.

21220385 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6487.

The product of its (nonzero) digits is 960, while the sum is 23.

The square root of 21220385 is about 4606.5589109443. The cubic root of 21220385 is about 276.8541808763.

Adding to 21220385 its reverse (58302212), we get a palindrome (79522597).

The spelling of 21220385 in words is "twenty-one million, two hundred twenty thousand, three hundred eighty-five".