77993578661 has 8 divisors (see below), whose sum is σ = 78073983000. Its totient is φ = 77913214720.

The previous prime is 77993578643. The next prime is 77993578679. The reversal of 77993578661 is 16687539977.

It is an interprime number because it is at equal distance from previous prime (77993578643) and next prime (77993578679).

It can be written as a sum of positive squares in 4 ways, for example, as 44289025 + 77949289636 = 6655^2 + 279194^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 77993578661 - 2¹⁴ = 77993562277 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 77993578591 and 77993578600.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77993578601) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5100335 + ... + 5115603.

It is an arithmetic number, because the mean of its divisors is an integer number (9759247875).

Almost surely, 2^77993578661 is an apocalyptic number.

It is an amenable number.

77993578661 is a deficient number, since it is larger than the sum of its proper divisors (80404339).

77993578661 is a wasteful number, since it uses less digits than its factorization.

77993578661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20199.

The product of its digits is 120022560, while the sum is 68.

The spelling of 77993578661 in words is "seventy-seven billion, nine hundred ninety-three million, five hundred seventy-eight thousand, six hundred sixty-one".