9781997 has 2 divisors, whose sum is σ = 9781998. Its totient is φ = 9781996.

The previous prime is 9781991. The next prime is 9782011. The reversal of 9781997 is 7991879.

9781997 is digitally balanced in base 2 and base 3, because in such bases it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 8128201 + 1653796 = 2851^2 + 1286^2 .

It is a cyclic number.

It is not a de Polignac number, because 9781997 - 2¹⁰ = 9780973 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9781991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4890998 + 4890999.

It is an arithmetic number, because the mean of its divisors is an integer number (4890999).

Almost surely, 2^9781997 is an apocalyptic number.

It is an amenable number.

9781997 is a deficient number, since it is larger than the sum of its proper divisors (1).

9781997 is an equidigital number, since it uses as much as digits as its factorization.

9781997 is an evil number, because the sum of its binary digits is even.

The product of its digits is 285768, while the sum is 50.

The square root of 9781997 is about 3127.6184230177. The cubic root of 9781997 is about 213.8663750770.

The spelling of 9781997 in words is "nine million, seven hundred eighty-one thousand, nine hundred ninety-seven".