997821173 has 2 divisors, whose sum is σ = 997821174. Its totient is φ = 997821172.

The previous prime is 997821163. The next prime is 997821257. The reversal of 997821173 is 371128799.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 920697649 + 77123524 = 30343^2 + 8782^2 .

It is an emirp because it is prime and its reverse (371128799) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 997821173 - 2⁶ = 997821109 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (997821163) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 498910586 + 498910587.

It is an arithmetic number, because the mean of its divisors is an integer number (498910587).

Almost surely, 2^997821173 is an apocalyptic number.

It is an amenable number.

997821173 is a deficient number, since it is larger than the sum of its proper divisors (1).

997821173 is an equidigital number, since it uses as much as digits as its factorization.

997821173 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 190512, while the sum is 47.

The square root of 997821173 is about 31588.3075361755. The cubic root of 997821173 is about 999.2731962176.

The spelling of 997821173 in words is "nine hundred ninety-seven million, eight hundred twenty-one thousand, one hundred seventy-three".