309906681 has 32 divisors (see below), whose sum is σ = 483214080. Its totient is φ = 173021184.

The previous prime is 309906647. The next prime is 309906689. The reversal of 309906681 is 186609903.

It is not a de Polignac number, because 309906681 - 2¹¹ = 309904633 is a prime.

It is a super-2 number, since 2×309906681² = 192084301856871522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (309906689) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 172335 + ... + 174123.

It is an arithmetic number, because the mean of its divisors is an integer number (15100440).

Almost surely, 2^309906681 is an apocalyptic number.

It is an amenable number.

309906681 is a deficient number, since it is larger than the sum of its proper divisors (173307399).

309906681 is a wasteful number, since it uses less digits than its factorization.

309906681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1985.

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

The square root of 309906681 is about 17604.1665806706. The cubic root of 309906681 is about 676.7220272544.

The spelling of 309906681 in words is "three hundred nine million, nine hundred six thousand, six hundred eighty-one".