77978537549 has 16 divisors (see below), whose sum is σ = 90322439040. Its totient is φ = 66533698560.

The previous prime is 77978537519. The next prime is 77978537569. The reversal of 77978537549 is 94573587977.

It is a cyclic number.

It is not a de Polignac number, because 77978537549 - 2²⁴ = 77961760333 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77978537519) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 513644 + ... + 647909.

It is an arithmetic number, because the mean of its divisors is an integer number (5645152440).

Almost surely, 2^77978537549 is an apocalyptic number.

It is an amenable number.

77978537549 is a deficient number, since it is larger than the sum of its proper divisors (12343901491).

77978537549 is a wasteful number, since it uses less digits than its factorization.

77978537549 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1161940.

The product of its digits is 466754400, while the sum is 71.

The spelling of 77978537549 in words is "seventy-seven billion, nine hundred seventy-eight million, five hundred thirty-seven thousand, five hundred forty-nine".