21218579 has 8 divisors (see below), whose sum is σ = 21546000. Its totient is φ = 20893312.

The previous prime is 21218551. The next prime is 21218599. The reversal of 21218579 is 97581212.

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 21218579 - 2¹⁶ = 21153043 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21218599) 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 7 ways as a sum of consecutive naturals, for example, 37007 + ... + 37575.

It is an arithmetic number, because the mean of its divisors is an integer number (2693250).

Almost surely, 2^21218579 is an apocalyptic number.

21218579 is a deficient number, since it is larger than the sum of its proper divisors (327421).

21218579 is an equidigital number, since it uses as much as digits as its factorization.

21218579 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1077.

The product of its digits is 10080, while the sum is 35.

The square root of 21218579 is about 4606.3628819276. The cubic root of 21218579 is about 276.8463265916.

The spelling of 21218579 in words is "twenty-one million, two hundred eighteen thousand, five hundred seventy-nine".