20218091 has 2 divisors, whose sum is σ = 20218092. Its totient is φ = 20218090.

The previous prime is 20218067. The next prime is 20218123. The reversal of 20218091 is 19081202.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20218091 - 2⁶ = 20218027 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20218291) by changing a digit.

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 as a sum of consecutive naturals, namely, 10109045 + 10109046.

It is an arithmetic number, because the mean of its divisors is an integer number (10109046).

Almost surely, 2^20218091 is an apocalyptic number.

20218091 is a deficient number, since it is larger than the sum of its proper divisors (1).

20218091 is an equidigital number, since it uses as much as digits as its factorization.

20218091 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 288, while the sum is 23.

The square root of 20218091 is about 4496.4531577678. The cubic root of 20218091 is about 272.4248469914.

Adding to 20218091 its reverse (19081202), we get a palindrome (39299293).

The spelling of 20218091 in words is "twenty million, two hundred eighteen thousand, ninety-one".