685981349 has 4 divisors (see below), whose sum is σ = 686351820. Its totient is φ = 685610880.

The previous prime is 685981321. The next prime is 685981367. The reversal of 685981349 is 943189586.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 943189586 = 2 ⋅471594793.

It can be written as a sum of positive squares in 2 ways, for example, as 29084449 + 656896900 = 5393^2 + 25630^2 .

It is a cyclic number.

It is not a de Polignac number, because 685981349 - 2²⁸ = 417545893 is a prime.

It is a super-2 number, since 2×685981349² = 941140822351719602, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 685981349.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (685981319) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 182444 + ... + 186165.

It is an arithmetic number, because the mean of its divisors is an integer number (171587955).

Almost surely, 2^685981349 is an apocalyptic number.

It is an amenable number.

685981349 is a deficient number, since it is larger than the sum of its proper divisors (370471).

685981349 is a wasteful number, since it uses less digits than its factorization.

685981349 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 370470.

The product of its digits is 1866240, while the sum is 53.

The square root of 685981349 is about 26191.2456557530. The cubic root of 685981349 is about 881.9367420691.

The spelling of 685981349 in words is "six hundred eighty-five million, nine hundred eighty-one thousand, three hundred forty-nine".