20181818381 has 2 divisors, whose sum is σ = 20181818382. Its totient is φ = 20181818380.

The previous prime is 20181818357. The next prime is 20181818407. The reversal of 20181818381 is 18381818102.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13667714281 + 6514104100 = 116909^2 + 80710^2 .

It is a cyclic number.

It is not a de Polignac number, because 20181818381 - 2¹⁸ = 20181556237 is a prime.

It is a super-2 number, since 2×20181818381² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20181818581) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10090909190 + 10090909191.

It is an arithmetic number, because the mean of its divisors is an integer number (10090909191).

Almost surely, 2^20181818381 is an apocalyptic number.

It is an amenable number.

20181818381 is a deficient number, since it is larger than the sum of its proper divisors (1).

20181818381 is an equidigital number, since it uses as much as digits as its factorization.

20181818381 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 24576, while the sum is 41.

The spelling of 20181818381 in words is "twenty billion, one hundred eighty-one million, eight hundred eighteen thousand, three hundred eighty-one".