77121809477 has 2 divisors, whose sum is σ = 77121809478. Its totient is φ = 77121809476.

The previous prime is 77121809449. The next prime is 77121809507. The reversal of 77121809477 is 77490812177.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 72691708996 + 4430100481 = 269614^2 + 66559^2 .

It is an emirp because it is prime and its reverse (77490812177) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 77121809477 - 2¹⁴ = 77121793093 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77121809447) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38560904738 + 38560904739.

It is an arithmetic number, because the mean of its divisors is an integer number (38560904739).

Almost surely, 2^77121809477 is an apocalyptic number.

It is an amenable number.

77121809477 is a deficient number, since it is larger than the sum of its proper divisors (1).

77121809477 is an equidigital number, since it uses as much as digits as its factorization.

77121809477 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1382976, while the sum is 53.

The spelling of 77121809477 in words is "seventy-seven billion, one hundred twenty-one million, eight hundred nine thousand, four hundred seventy-seven".