21821385 has 8 divisors (see below), whose sum is σ = 34914240. Its totient is φ = 11638064.

The previous prime is 21821383. The next prime is 21821399. The reversal of 21821385 is 58312812.

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 21821385 - 2¹ = 21821383 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21821383) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 727365 + ... + 727394.

It is an arithmetic number, because the mean of its divisors is an integer number (4364280).

Almost surely, 2^21821385 is an apocalyptic number.

It is an amenable number.

21821385 is a deficient number, since it is larger than the sum of its proper divisors (13092855).

21821385 is a wasteful number, since it uses less digits than its factorization.

21821385 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1454767.

The product of its digits is 3840, while the sum is 30.

The square root of 21821385 is about 4671.3365325140. The cubic root of 21821385 is about 279.4435590391.

The spelling of 21821385 in words is "twenty-one million, eight hundred twenty-one thousand, three hundred eighty-five".