8561861993 has 2 divisors, whose sum is σ = 8561861994. Its totient is φ = 8561861992.

The previous prime is 8561861977. The next prime is 8561862041. The reversal of 8561861993 is 3991681658.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6446965849 + 2114896144 = 80293^2 + 45988^2 .

It is a cyclic number.

It is not a de Polignac number, because 8561861993 - 2⁴ = 8561861977 is a prime.

It is not a weakly prime, because it can be changed into another prime (8561861923) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4280930996 + 4280930997.

It is an arithmetic number, because the mean of its divisors is an integer number (4280930997).

Almost surely, 2^8561861993 is an apocalyptic number.

It is an amenable number.

8561861993 is a deficient number, since it is larger than the sum of its proper divisors (1).

8561861993 is an equidigital number, since it uses as much as digits as its factorization.

8561861993 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2799360, while the sum is 56.

The square root of 8561861993 is about 92530.3301247758. The cubic root of 8561861993 is about 2045.7665554828.

The spelling of 8561861993 in words is "eight billion, five hundred sixty-one million, eight hundred sixty-one thousand, nine hundred ninety-three".