8561820997 has 2 divisors, whose sum is σ = 8561820998. Its totient is φ = 8561820996.

The previous prime is 8561820973. The next prime is 8561821019. The reversal of 8561820997 is 7990281658.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 7875852516 + 685968481 = 88746^2 + 26191^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-8561820997 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8561820937) 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, 4280910498 + 4280910499.

It is an arithmetic number, because the mean of its divisors is an integer number (4280910499).

Almost surely, 2^8561820997 is an apocalyptic number.

It is an amenable number.

8561820997 is a deficient number, since it is larger than the sum of its proper divisors (1).

8561820997 is an equidigital number, since it uses as much as digits as its factorization.

8561820997 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2177280, while the sum is 55.

The square root of 8561820997 is about 92530.1085971480. The cubic root of 8561820997 is about 2045.7632902904.

The spelling of 8561820997 in words is "eight billion, five hundred sixty-one million, eight hundred twenty thousand, nine hundred ninety-seven".