77778503987 has 4 divisors (see below), whose sum is σ = 81872109480. Its totient is φ = 73684898496.

The previous prime is 77778503981. The next prime is 77778503993. The reversal of 77778503987 is 78930587777.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 78930587777 = 3361 ⋅23484257.

It is an interprime number because it is at equal distance from previous prime (77778503981) and next prime (77778503993).

It is a cyclic number.

It is not a de Polignac number, because 77778503987 - 2¹⁸ = 77778241843 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (77778503981) 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, 2046802718 + ... + 2046802755.

It is an arithmetic number, because the mean of its divisors is an integer number (20468027370).

Almost surely, 2^77778503987 is an apocalyptic number.

77778503987 is a deficient number, since it is larger than the sum of its proper divisors (4093605493).

77778503987 is a wasteful number, since it uses less digits than its factorization.

77778503987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4093605492.

The product of its (nonzero) digits is 145212480, while the sum is 68.

The spelling of 77778503987 in words is "seventy-seven billion, seven hundred seventy-eight million, five hundred three thousand, nine hundred eighty-seven".