77971756687 has 4 divisors (see below), whose sum is σ = 85060098216. Its totient is φ = 70883415160.

The previous prime is 77971756663. The next prime is 77971756693. The reversal of 77971756687 is 78665717977.

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

It is a cyclic number.

It is not a de Polignac number, because 77971756687 - 2¹¹ = 77971754639 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 (77971756637) 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, 3544170748 + ... + 3544170769.

It is an arithmetic number, because the mean of its divisors is an integer number (21265024554).

Almost surely, 2^77971756687 is an apocalyptic number.

77971756687 is a deficient number, since it is larger than the sum of its proper divisors (7088341529).

77971756687 is a wasteful number, since it uses less digits than its factorization.

77971756687 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7088341528.

The product of its digits is 217818720, while the sum is 70.

The spelling of 77971756687 in words is "seventy-seven billion, nine hundred seventy-one million, seven hundred fifty-six thousand, six hundred eighty-seven".