686637481 has 2 divisors, whose sum is σ = 686637482. Its totient is φ = 686637480.

The previous prime is 686637467. The next prime is 686637517. The reversal of 686637481 is 184736686.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 435097881 + 251539600 = 20859^2 + 15860^2 .

It is a cyclic number.

It is not a de Polignac number, because 686637481 - 2¹⁷ = 686506409 is a prime.

It is a super-2 number, since 2×686637481² = 942942060628050722, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (686637461) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 343318740 + 343318741.

It is an arithmetic number, because the mean of its divisors is an integer number (343318741).

Almost surely, 2^686637481 is an apocalyptic number.

It is an amenable number.

686637481 is a deficient number, since it is larger than the sum of its proper divisors (1).

686637481 is an equidigital number, since it uses as much as digits as its factorization.

686637481 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1161216, while the sum is 49.

The square root of 686637481 is about 26203.7684503584. The cubic root of 686637481 is about 882.2178393718.

The spelling of 686637481 in words is "six hundred eighty-six million, six hundred thirty-seven thousand, four hundred eighty-one".