21818899 has 2 divisors, whose sum is σ = 21818900. Its totient is φ = 21818898.

The previous prime is 21818893. The next prime is 21818921. The reversal of 21818899 is 99881812.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21818899 - 2²¹ = 19721747 is a prime.

It is not a weakly prime, because it can be changed into another prime (21818893) 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 as a sum of consecutive naturals, namely, 10909449 + 10909450.

It is an arithmetic number, because the mean of its divisors is an integer number (10909450).

Almost surely, 2^21818899 is an apocalyptic number.

21818899 is a deficient number, since it is larger than the sum of its proper divisors (1).

21818899 is an equidigital number, since it uses as much as digits as its factorization.

21818899 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 82944, while the sum is 46.

The square root of 21818899 is about 4671.0704340654. The cubic root of 21818899 is about 279.4329467724.

It can be divided in two parts, 218188 and 99, that multiplied together give a palindrome (21600612).

The spelling of 21818899 in words is "twenty-one million, eight hundred eighteen thousand, eight hundred ninety-nine".