686392991 has 2 divisors, whose sum is σ = 686392992. Its totient is φ = 686392990.

The previous prime is 686392891. The next prime is 686393017. The reversal of 686392991 is 199293686.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 686392991 - 2²² = 682198687 is a prime.

It is a super-2 number, since 2×686392991² = 942270676187852162, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (686392891) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343196495 + 343196496.

It is an arithmetic number, because the mean of its divisors is an integer number (343196496).

Almost surely, 2^686392991 is an apocalyptic number.

686392991 is a deficient number, since it is larger than the sum of its proper divisors (1).

686392991 is an equidigital number, since it uses as much as digits as its factorization.

686392991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1259712, while the sum is 53.

The square root of 686392991 is about 26199.1028663197. The cubic root of 686392991 is about 882.1131169377.

The spelling of 686392991 in words is "six hundred eighty-six million, three hundred ninety-two thousand, nine hundred ninety-one".