678640731877 has 2 divisors, whose sum is σ = 678640731878. Its totient is φ = 678640731876.

The previous prime is 678640731827. The next prime is 678640731943. The reversal of 678640731877 is 778137046876.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 354645261441 + 323995470436 = 595521^2 + 569206^2 .

It is a cyclic number.

It is not a de Polignac number, because 678640731877 - 2¹⁹ = 678640207589 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (678640731827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 339320365938 + 339320365939.

It is an arithmetic number, because the mean of its divisors is an integer number (339320365939).

Almost surely, 2^678640731877 is an apocalyptic number.

It is an amenable number.

678640731877 is a deficient number, since it is larger than the sum of its proper divisors (1).

678640731877 is an equidigital number, since it uses as much as digits as its factorization.

678640731877 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 66382848, while the sum is 64.

The spelling of 678640731877 in words is "six hundred seventy-eight billion, six hundred forty million, seven hundred thirty-one thousand, eight hundred seventy-seven".