18861863591 has 2 divisors, whose sum is σ = 18861863592. Its totient is φ = 18861863590.

The previous prime is 18861863561. The next prime is 18861863641. The reversal of 18861863591 is 19536816881.

It is a weak prime.

It is an emirp because it is prime and its reverse (19536816881) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18861863591 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18861863551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9430931795 + 9430931796.

It is an arithmetic number, because the mean of its divisors is an integer number (9430931796).

Almost surely, 2^18861863591 is an apocalyptic number.

18861863591 is a deficient number, since it is larger than the sum of its proper divisors (1).

18861863591 is an equidigital number, since it uses as much as digits as its factorization.

18861863591 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2488320, while the sum is 56.

The spelling of 18861863591 in words is "eighteen billion, eight hundred sixty-one million, eight hundred sixty-three thousand, five hundred ninety-one".