681906309 has 8 divisors (see below), whose sum is σ = 1039095360. Its totient is φ = 389660736.

The previous prime is 681906299. The next prime is 681906311. The reversal of 681906309 is 903609186.

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

It is not a de Polignac number, because 681906309 - 2⁴ = 681906293 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681906209) 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, 16235844 + ... + 16235885.

It is an arithmetic number, because the mean of its divisors is an integer number (129886920).

Almost surely, 2^681906309 is an apocalyptic number.

It is an amenable number.

681906309 is a deficient number, since it is larger than the sum of its proper divisors (357189051).

681906309 is a wasteful number, since it uses less digits than its factorization.

681906309 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32471739.

The product of its (nonzero) digits is 69984, while the sum is 42.

The square root of 681906309 is about 26113.3358458853. The cubic root of 681906309 is about 880.1869046012.

The spelling of 681906309 in words is "six hundred eighty-one million, nine hundred six thousand, three hundred nine".