77128687 has 2 divisors, whose sum is σ = 77128688. Its totient is φ = 77128686.

The previous prime is 77128673. The next prime is 77128697. The reversal of 77128687 is 78682177.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-77128687 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77128607) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38564343 + 38564344.

It is an arithmetic number, because the mean of its divisors is an integer number (38564344).

Almost surely, 2^77128687 is an apocalyptic number.

77128687 is a deficient number, since it is larger than the sum of its proper divisors (1).

77128687 is an equidigital number, since it uses as much as digits as its factorization.

77128687 is an evil number, because the sum of its binary digits is even.

The product of its digits is 263424, while the sum is 46.

The square root of 77128687 is about 8782.2939486219. The cubic root of 77128687 is about 425.6689571092.

It can be divided in two parts, 77128 and 687, that added together give a triangular number (77815 = T₃₉₄).

The spelling of 77128687 in words is "seventy-seven million, one hundred twenty-eight thousand, six hundred eighty-seven".