77591609 has 4 divisors (see below), whose sum is σ = 77638116. Its totient is φ = 77545104.

The previous prime is 77591599. The next prime is 77591659. The reversal of 77591609 is 90619577.

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 43626025 + 33965584 = 6605^2 + 5828^2 .

It is a cyclic number.

It is not a de Polignac number, because 77591609 - 2⁴ = 77591593 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 77591609.

It is not an unprimeable number, because it can be changed into a prime (77591659) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20654 + ... + 24119.

It is an arithmetic number, because the mean of its divisors is an integer number (19409529).

Almost surely, 2^77591609 is an apocalyptic number.

It is an amenable number.

77591609 is a deficient number, since it is larger than the sum of its proper divisors (46507).

77591609 is a wasteful number, since it uses less digits than its factorization.

77591609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46506.

The product of its (nonzero) digits is 119070, while the sum is 44.

The square root of 77591609 is about 8808.6099357390. The cubic root of 77591609 is about 426.5188726258.

The spelling of 77591609 in words is "seventy-seven million, five hundred ninety-one thousand, six hundred nine".