1648778917 has 2 divisors, whose sum is σ = 1648778918. Its totient is φ = 1648778916.

The previous prime is 1648778909. The next prime is 1648778939. The reversal of 1648778917 is 7198778461.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 970384801 + 678394116 = 31151^2 + 26046^2 .

It is a cyclic number.

It is not a de Polignac number, because 1648778917 - 2³ = 1648778909 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1648778017) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 824389458 + 824389459.

It is an arithmetic number, because the mean of its divisors is an integer number (824389459).

Almost surely, 2^1648778917 is an apocalyptic number.

It is an amenable number.

1648778917 is a deficient number, since it is larger than the sum of its proper divisors (1).

1648778917 is an equidigital number, since it uses as much as digits as its factorization.

1648778917 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4741632, while the sum is 58.

The square root of 1648778917 is about 40605.1587486122. The cubic root of 1648778917 is about 1181.3741811648.

The spelling of 1648778917 in words is "one billion, six hundred forty-eight million, seven hundred seventy-eight thousand, nine hundred seventeen".