978173309 has 2 divisors, whose sum is σ = 978173310. Its totient is φ = 978173308.

The previous prime is 978173293. The next prime is 978173323. The reversal of 978173309 is 903371879.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 758837209 + 219336100 = 27547^2 + 14810^2 .

It is an emirp because it is prime and its reverse (903371879) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 978173309 - 2⁴ = 978173293 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (978173389) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 489086654 + 489086655.

It is an arithmetic number, because the mean of its divisors is an integer number (489086655).

Almost surely, 2^978173309 is an apocalyptic number.

It is an amenable number.

978173309 is a deficient number, since it is larger than the sum of its proper divisors (1).

978173309 is an equidigital number, since it uses as much as digits as its factorization.

978173309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 285768, while the sum is 47.

The square root of 978173309 is about 31275.7623248419. The cubic root of 978173309 is about 992.6708511422.

The spelling of 978173309 in words is "nine hundred seventy-eight million, one hundred seventy-three thousand, three hundred nine".