77785121 has 2 divisors, whose sum is σ = 77785122. Its totient is φ = 77785120.

The previous prime is 77785073. The next prime is 77785129. The reversal of 77785121 is 12158777.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 73290721 + 4494400 = 8561^2 + 2120^2 .

It is an emirp because it is prime and its reverse (12158777) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 77785121 - 2²⁶ = 10676257 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (77785129) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38892560 + 38892561.

It is an arithmetic number, because the mean of its divisors is an integer number (38892561).

Almost surely, 2^77785121 is an apocalyptic number.

It is an amenable number.

77785121 is a deficient number, since it is larger than the sum of its proper divisors (1).

77785121 is an equidigital number, since it uses as much as digits as its factorization.

77785121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 27440, while the sum is 38.

The square root of 77785121 is about 8819.5873486235. The cubic root of 77785121 is about 426.8731549217.

The spelling of 77785121 in words is "seventy-seven million, seven hundred eighty-five thousand, one hundred twenty-one".