77731309 has 2 divisors, whose sum is σ = 77731310. Its totient is φ = 77731308.

The previous prime is 77731307. The next prime is 77731321. The reversal of 77731309 is 90313777.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 55547209 + 22184100 = 7453^2 + 4710^2 .

It is a cyclic number.

It is not a de Polignac number, because 77731309 - 2¹ = 77731307 is a prime.

Together with 77731307, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77731301) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38865654 + 38865655.

It is an arithmetic number, because the mean of its divisors is an integer number (38865655).

Almost surely, 2^77731309 is an apocalyptic number.

It is an amenable number.

77731309 is a deficient number, since it is larger than the sum of its proper divisors (1).

77731309 is an equidigital number, since it uses as much as digits as its factorization.

77731309 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 27783, while the sum is 37.

The square root of 77731309 is about 8816.5361111947. The cubic root of 77731309 is about 426.7746948004.

The spelling of 77731309 in words is "seventy-seven million, seven hundred thirty-one thousand, three hundred nine".