77691557 has 2 divisors, whose sum is σ = 77691558. Its totient is φ = 77691556.

The previous prime is 77691529. The next prime is 77691599. The reversal of 77691557 is 75519677.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 39363076 + 38328481 = 6274^2 + 6191^2 .

It is an emirp because it is prime and its reverse (75519677) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-77691557 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77691457) 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, 38845778 + 38845779.

It is an arithmetic number, because the mean of its divisors is an integer number (38845779).

Almost surely, 2^77691557 is an apocalyptic number.

It is an amenable number.

77691557 is a deficient number, since it is larger than the sum of its proper divisors (1).

77691557 is an equidigital number, since it uses as much as digits as its factorization.

77691557 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 463050, while the sum is 47.

The square root of 77691557 is about 8814.2814227820. The cubic root of 77691557 is about 426.7019311537.

The spelling of 77691557 in words is "seventy-seven million, six hundred ninety-one thousand, five hundred fifty-seven".