21820318 has 16 divisors (see below), whose sum is σ = 35325360. Its totient is φ = 10048896.

The previous prime is 21820301. The next prime is 21820319. The reversal of 21820318 is 81302812.

It is a super-2 number, since 2×21820318² = 952252555242248, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21820292 and 21820301.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21820319) 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, 21846 + ... + 22822.

It is an arithmetic number, because the mean of its divisors is an integer number (2207835).

Almost surely, 2^21820318 is an apocalyptic number.

21820318 is a deficient number, since it is larger than the sum of its proper divisors (13505042).

21820318 is a wasteful number, since it uses less digits than its factorization.

21820318 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1851.

The product of its (nonzero) digits is 768, while the sum is 25.

The square root of 21820318 is about 4671.2223239747. Note that the first 3 decimals coincide. The cubic root of 21820318 is about 279.4390043154.

The spelling of 21820318 in words is "twenty-one million, eight hundred twenty thousand, three hundred eighteen".