77989909 has 2 divisors, whose sum is σ = 77989910. Its totient is φ = 77989908.

The previous prime is 77989883. The next prime is 77989921. The reversal of 77989909 is 90998977.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 72335025 + 5654884 = 8505^2 + 2378^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-77989909 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77989939) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38994954 + 38994955.

It is an arithmetic number, because the mean of its divisors is an integer number (38994955).

Almost surely, 2^77989909 is an apocalyptic number.

It is an amenable number.

77989909 is a deficient number, since it is larger than the sum of its proper divisors (1).

77989909 is an equidigital number, since it uses as much as digits as its factorization.

77989909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2571912, while the sum is 58.

The square root of 77989909 is about 8831.1895574719. The cubic root of 77989909 is about 427.2474419911.

The spelling of 77989909 in words is "seventy-seven million, nine hundred eighty-nine thousand, nine hundred nine".