77396909209 has 27 divisors (see below), whose sum is σ = 81440450973. Its totient is φ = 73552421952.

The previous prime is 77396909179. The next prime is 77396909267. The reversal of 77396909209 is 90290969377.

The square root of 77396909209 is 278203.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 19306268809 + 58090640400 = 138947^2 + 241020^2 .

It is not a de Polignac number, because 77396909209 - 2⁹ = 77396908697 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (77396900209) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 751426252 + ... + 751426354.

It is an arithmetic number, because the mean of its divisors is an integer number (3016312999).

Almost surely, 2^77396909209 is an apocalyptic number.

77396909209 is the 278203-rd square number.

77396909209 is the 139102-nd centered octagonal number.

It is an amenable number.

77396909209 is a deficient number, since it is larger than the sum of its proper divisors (4043541764).

77396909209 is an frugal number, since it uses more digits than its factorization.

77396909209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 426 (or 213 counting only the distinct ones).

The product of its (nonzero) digits is 11573604, while the sum is 61.

The spelling of 77396909209 in words is "seventy-seven billion, three hundred ninety-six million, nine hundred nine thousand, two hundred nine".