685508981 has 8 divisors (see below), whose sum is σ = 695210880. Its totient is φ = 675865872.

The previous prime is 685508947. The next prime is 685508987. The reversal of 685508981 is 189805586.

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-685508981 is a prime.

It is a super-2 number, since 2×685508981² = 939845126063316722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (685508987) 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, 9056 + ... + 38118.

It is an arithmetic number, because the mean of its divisors is an integer number (86901360).

Almost surely, 2^685508981 is an apocalyptic number.

It is an amenable number.

685508981 is a deficient number, since it is larger than the sum of its proper divisors (9701899).

685508981 is a wasteful number, since it uses less digits than its factorization.

685508981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29395.

The product of its (nonzero) digits is 691200, while the sum is 50.

The square root of 685508981 is about 26182.2264332123. The cubic root of 685508981 is about 881.7342611728.

The spelling of 685508981 in words is "six hundred eighty-five million, five hundred eight thousand, nine hundred eighty-one".