21818398 has 16 divisors (see below), whose sum is σ = 39029760. Its totient is φ = 8944056.

The previous prime is 21818393. The next prime is 21818399. The reversal of 21818398 is 89381812.

It is a self number, because there is not a number n which added to its sum of digits gives 21818398.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21818393) by changing a digit.

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, 33558 + ... + 34201.

It is an arithmetic number, because the mean of its divisors is an integer number (2439360).

Almost surely, 2^21818398 is an apocalyptic number.

21818398 is a deficient number, since it is larger than the sum of its proper divisors (17211362).

21818398 is a wasteful number, since it uses less digits than its factorization.

21818398 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67791.

The product of its digits is 27648, while the sum is 40.

The square root of 21818398 is about 4671.0168057929. The cubic root of 21818398 is about 279.4308080000.

The spelling of 21818398 in words is "twenty-one million, eight hundred eighteen thousand, three hundred ninety-eight".