77909609 has 4 divisors (see below), whose sum is σ = 77932116. Its totient is φ = 77887104.

The previous prime is 77909591. The next prime is 77909641. The reversal of 77909609 is 90690977.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 35046400 + 42863209 = 5920^2 + 6547^2 .

It is a cyclic number.

It is not a de Polignac number, because 77909609 - 2⁸ = 77909353 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (77909659) 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 in 3 ways as a sum of consecutive naturals, for example, 4844 + ... + 13389.

It is an arithmetic number, because the mean of its divisors is an integer number (19483029).

Almost surely, 2^77909609 is an apocalyptic number.

It is an amenable number.

77909609 is a deficient number, since it is larger than the sum of its proper divisors (22507).

77909609 is a wasteful number, since it uses less digits than its factorization.

77909609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22506.

The product of its (nonzero) digits is 214326, while the sum is 47.

The square root of 77909609 is about 8826.6420002173. The cubic root of 77909609 is about 427.1007574114.

The spelling of 77909609 in words is "seventy-seven million, nine hundred nine thousand, six hundred nine".