18861643 has 2 divisors, whose sum is σ = 18861644. Its totient is φ = 18861642.

The previous prime is 18861637. The next prime is 18861673. The reversal of 18861643 is 34616881.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 18861643 - 2²¹ = 16764491 is a prime.

It is not a weakly prime, because it can be changed into another prime (18861673) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9430821 + 9430822.

It is an arithmetic number, because the mean of its divisors is an integer number (9430822).

Almost surely, 2^18861643 is an apocalyptic number.

18861643 is a deficient number, since it is larger than the sum of its proper divisors (1).

18861643 is an equidigital number, since it uses as much as digits as its factorization.

18861643 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 27648, while the sum is 37.

The square root of 18861643 is about 4342.9993092332. Note that the first 3 decimals coincide. The cubic root of 18861643 is about 266.1908809500.

The spelling of 18861643 in words is "eighteen million, eight hundred sixty-one thousand, six hundred forty-three".