21316218 has 128 divisors (see below), whose sum is σ = 57784320. Its totient is φ = 5080320.

The previous prime is 21316201. The next prime is 21316223. The reversal of 21316218 is 81261312.

It is a super-2 number, since 2×21316218² = 908762299647048, which contains 22 as substring.

It is an unprimeable number.

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 63 ways as a sum of consecutive naturals, for example, 495705 + ... + 495747.

It is an arithmetic number, because the mean of its divisors is an integer number (451440).

Almost surely, 2^21316218 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21316218, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28892160).

21316218 is an abundant number, since it is smaller than the sum of its proper divisors (36468102).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21316218 is a wasteful number, since it uses less digits than its factorization.

21316218 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 132.

The product of its digits is 576, while the sum is 24.

The square root of 21316218 is about 4616.9489925707. The cubic root of 21316218 is about 277.2703204632.

The spelling of 21316218 in words is "twenty-one million, three hundred sixteen thousand, two hundred eighteen".