77864989 has 2 divisors, whose sum is σ = 77864990. Its totient is φ = 77864988.

The previous prime is 77864987. The next prime is 77865017. The reversal of 77864989 is 98946877.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 65205625 + 12659364 = 8075^2 + 3558^2 .

It is a cyclic number.

It is not a de Polignac number, because 77864989 - 2¹ = 77864987 is a prime.

Together with 77864987, 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 (77864987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38932494 + 38932495.

It is an arithmetic number, because the mean of its divisors is an integer number (38932495).

Almost surely, 2^77864989 is an apocalyptic number.

It is an amenable number.

77864989 is a deficient number, since it is larger than the sum of its proper divisors (1).

77864989 is an equidigital number, since it uses as much as digits as its factorization.

77864989 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6096384, while the sum is 58.

The square root of 77864989 is about 8824.1140631794. The cubic root of 77864989 is about 427.0192061739.

The spelling of 77864989 in words is "seventy-seven million, eight hundred sixty-four thousand, nine hundred eighty-nine".