685656731 has 8 divisors (see below), whose sum is σ = 705386400. Its totient is φ = 665990208.

The previous prime is 685656701. The next prime is 685656757. The reversal of 685656731 is 137656586.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-685656731 is a prime.

It is a super-2 number, since 2×685656731² = 940250305531212722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (685656701) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6695 + ... + 37631.

It is an arithmetic number, because the mean of its divisors is an integer number (88173300).

Almost surely, 2^685656731 is an apocalyptic number.

685656731 is a deficient number, since it is larger than the sum of its proper divisors (19729669).

685656731 is a wasteful number, since it uses less digits than its factorization.

685656731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31573.

The product of its digits is 907200, while the sum is 47.

The square root of 685656731 is about 26185.0478517798. The cubic root of 685656731 is about 881.7976043150.

The spelling of 685656731 in words is "six hundred eighty-five million, six hundred fifty-six thousand, seven hundred thirty-one".