685921906 has 8 divisors (see below), whose sum is σ = 1039070124. Its totient is φ = 339565200.

The previous prime is 685921897. The next prime is 685921913. The reversal of 685921906 is 609129586.

It can be written as a sum of positive squares in 2 ways, for example, as 602948025 + 82973881 = 24555^2 + 9109^2 .

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

It is a super-2 number, since 2×685921906² = 940977722261345672, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1697625 + ... + 1698028.

Almost surely, 2^685921906 is an apocalyptic number.

685921906 is a deficient number, since it is larger than the sum of its proper divisors (353148218).

685921906 is a wasteful number, since it uses less digits than its factorization.

685921906 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3395756.

The product of its (nonzero) digits is 233280, while the sum is 46.

The square root of 685921906 is about 26190.1108435990. The cubic root of 685921906 is about 881.9112668964.

The spelling of 685921906 in words is "six hundred eighty-five million, nine hundred twenty-one thousand, nine hundred six".