20018491 has 2 divisors, whose sum is σ = 20018492. Its totient is φ = 20018490.

The previous prime is 20018489. The next prime is 20018527. The reversal of 20018491 is 19481002.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20018491 - 2¹ = 20018489 is a prime.

Together with 20018489, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (20018891) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10009245 + 10009246.

It is an arithmetic number, because the mean of its divisors is an integer number (10009246).

Almost surely, 2^20018491 is an apocalyptic number.

20018491 is a deficient number, since it is larger than the sum of its proper divisors (1).

20018491 is an equidigital number, since it uses as much as digits as its factorization.

20018491 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 576, while the sum is 25.

The square root of 20018491 is about 4474.2028340253. The cubic root of 20018491 is about 271.5253897189.

Adding to 20018491 its reverse (19481002), we get a palindrome (39499493).

The spelling of 20018491 in words is "twenty million, eighteen thousand, four hundred ninety-one".