1978236917 has 2 divisors, whose sum is σ = 1978236918. Its totient is φ = 1978236916.

The previous prime is 1978236913. The next prime is 1978236929. The reversal of 1978236917 is 7196328791.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1889293156 + 88943761 = 43466^2 + 9431^2 .

It is a cyclic number.

It is not a de Polignac number, because 1978236917 - 2² = 1978236913 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1978236913) 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, 989118458 + 989118459.

It is an arithmetic number, because the mean of its divisors is an integer number (989118459).

Almost surely, 2^1978236917 is an apocalyptic number.

It is an amenable number.

1978236917 is a deficient number, since it is larger than the sum of its proper divisors (1).

1978236917 is an equidigital number, since it uses as much as digits as its factorization.

1978236917 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1143072, while the sum is 53.

The square root of 1978236917 is about 44477.3753384797. The cubic root of 1978236917 is about 1255.3344118174.

The spelling of 1978236917 in words is "one billion, nine hundred seventy-eight million, two hundred thirty-six thousand, nine hundred seventeen".