77121553309 has 2 divisors, whose sum is σ = 77121553310. Its totient is φ = 77121553308.

The previous prime is 77121553279. The next prime is 77121553321. The reversal of 77121553309 is 90335512177.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 64985226084 + 12136327225 = 254922^2 + 110165^2 .

It is a cyclic number.

It is not a de Polignac number, because 77121553309 - 2⁹ = 77121552797 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77121553349) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38560776654 + 38560776655.

It is an arithmetic number, because the mean of its divisors is an integer number (38560776655).

Almost surely, 2^77121553309 is an apocalyptic number.

It is an amenable number.

77121553309 is a deficient number, since it is larger than the sum of its proper divisors (1).

77121553309 is an equidigital number, since it uses as much as digits as its factorization.

77121553309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 198450, while the sum is 43.

The spelling of 77121553309 in words is "seventy-seven billion, one hundred twenty-one million, five hundred fifty-three thousand, three hundred nine".