685312993 has 4 divisors (see below), whose sum is σ = 725625540. Its totient is φ = 645000448.

The previous prime is 685312987. The next prime is 685313003. The reversal of 685312993 is 399213586.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 598878784 + 86434209 = 24472^2 + 9297^2 .

It is a cyclic number.

It is not a de Polignac number, because 685312993 - 2¹⁷ = 685181921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (685312933) 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, 20156248 + ... + 20156281.

It is an arithmetic number, because the mean of its divisors is an integer number (181406385).

Almost surely, 2^685312993 is an apocalyptic number.

It is an amenable number.

685312993 is a deficient number, since it is larger than the sum of its proper divisors (40312547).

685312993 is a wasteful number, since it uses less digits than its factorization.

685312993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40312546.

The product of its digits is 349920, while the sum is 46.

The square root of 685312993 is about 26178.4833976302. The cubic root of 685312993 is about 881.6502234672.

The spelling of 685312993 in words is "six hundred eighty-five million, three hundred twelve thousand, nine hundred ninety-three".