997105661 has 2 divisors, whose sum is σ = 997105662. Its totient is φ = 997105660.

The previous prime is 997105657. The next prime is 997105667. The reversal of 997105661 is 166501799.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 880249561 + 116856100 = 29669^2 + 10810^2 .

It is an emirp because it is prime and its reverse (166501799) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 997105661 - 2² = 997105657 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (997105667) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 498552830 + 498552831.

It is an arithmetic number, because the mean of its divisors is an integer number (498552831).

Almost surely, 2^997105661 is an apocalyptic number.

It is an amenable number.

997105661 is a deficient number, since it is larger than the sum of its proper divisors (1).

997105661 is an equidigital number, since it uses as much as digits as its factorization.

997105661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 102060, while the sum is 44.

The square root of 997105661 is about 31576.9799220888. The cubic root of 997105661 is about 999.0342880339.

The spelling of 997105661 in words is "nine hundred ninety-seven million, one hundred five thousand, six hundred sixty-one".