21359218 has 16 divisors (see below), whose sum is σ = 32931360. Its totient is φ = 10384416.

The previous prime is 21359209. The next prime is 21359243. The reversal of 21359218 is 81295312.

It is a self number, because there is not a number n which added to its sum of digits gives 21359218.

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, 25998 + ... + 26806.

It is an arithmetic number, because the mean of its divisors is an integer number (2058210).

Almost surely, 2^21359218 is an apocalyptic number.

21359218 is a deficient number, since it is larger than the sum of its proper divisors (11572142).

21359218 is a wasteful number, since it uses less digits than its factorization.

21359218 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1161.

The product of its digits is 4320, while the sum is 31.

The square root of 21359218 is about 4621.6034014182. The cubic root of 21359218 is about 277.4566358125.

The spelling of 21359218 in words is "twenty-one million, three hundred fifty-nine thousand, two hundred eighteen".