686631491 has 16 divisors (see below), whose sum is σ = 845713344. Its totient is φ = 542865024.

The previous prime is 686631487. The next prime is 686631499. The reversal of 686631491 is 194136686.

It is a happy number.

It is not a de Polignac number, because 686631491 - 2² = 686631487 is a prime.

It is not an unprimeable number, because it can be changed into a prime (686631499) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 201881 + ... + 205253.

It is an arithmetic number, because the mean of its divisors is an integer number (52857084).

Almost surely, 2^686631491 is an apocalyptic number.

686631491 is a deficient number, since it is larger than the sum of its proper divisors (159081853).

686631491 is a wasteful number, since it uses less digits than its factorization.

686631491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5630.

The product of its digits is 186624, while the sum is 44.

The square root of 686631491 is about 26203.6541535718. The cubic root of 686631491 is about 882.2152739714.

The spelling of 686631491 in words is "six hundred eighty-six million, six hundred thirty-one thousand, four hundred ninety-one".