686840971 has 2 divisors, whose sum is σ = 686840972. Its totient is φ = 686840970.

The previous prime is 686840963. The next prime is 686840983. The reversal of 686840971 is 179048686.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 686840971 - 2³ = 686840963 is a prime.

It is not a weakly prime, because it can be changed into another prime (686840911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343420485 + 343420486.

It is an arithmetic number, because the mean of its divisors is an integer number (343420486).

Almost surely, 2^686840971 is an apocalyptic number.

686840971 is a deficient number, since it is larger than the sum of its proper divisors (1).

686840971 is an equidigital number, since it uses as much as digits as its factorization.

686840971 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 580608, while the sum is 49.

The square root of 686840971 is about 26207.6510011867. The cubic root of 686840971 is about 882.3049813168.

The spelling of 686840971 in words is "six hundred eighty-six million, eight hundred forty thousand, nine hundred seventy-one".