778315261 has 2 divisors, whose sum is σ = 778315262. Its totient is φ = 778315260.

The previous prime is 778315249. The next prime is 778315273. The reversal of 778315261 is 162513877.

It is a balanced prime because it is at equal distance from previous prime (778315249) and next prime (778315273).

It can be written as a sum of positive squares in only one way, i.e., 656896900 + 121418361 = 25630^2 + 11019^2 .

It is a cyclic number.

It is not a de Polignac number, because 778315261 - 2⁷ = 778315133 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (778315061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 389157630 + 389157631.

It is an arithmetic number, because the mean of its divisors is an integer number (389157631).

Almost surely, 2^778315261 is an apocalyptic number.

778315261 is the 12477-th centered decagonal number.

It is an amenable number.

778315261 is a deficient number, since it is larger than the sum of its proper divisors (1).

778315261 is an equidigital number, since it uses as much as digits as its factorization.

778315261 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 70560, while the sum is 40.

The square root of 778315261 is about 27898.3021167956. The cubic root of 778315261 is about 919.8531826995.

The spelling of 778315261 in words is "seven hundred seventy-eight million, three hundred fifteen thousand, two hundred sixty-one".