309809381 has 16 divisors (see below), whose sum is σ = 366551040. Its totient is φ = 256238640.

The previous prime is 309809363. The next prime is 309809387. The reversal of 309809381 is 183908903.

309809381 is nontrivially palindromic in base 6.

It is not a de Polignac number, because 309809381 - 2⁶ = 309809317 is a prime.

It is a super-2 number, since 2×309809381² = 191963705111206322, 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 (309809387) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 80360 + ... + 84126.

It is an arithmetic number, because the mean of its divisors is an integer number (22909440).

Almost surely, 2^309809381 is an apocalyptic number.

309809381 is a gapful number since it is divisible by the number (31) formed by its first and last digit.

It is an amenable number.

309809381 is a deficient number, since it is larger than the sum of its proper divisors (56741659).

309809381 is a wasteful number, since it uses less digits than its factorization.

309809381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4184.

The product of its (nonzero) digits is 46656, while the sum is 41.

The square root of 309809381 is about 17601.4028134123. The cubic root of 309809381 is about 676.6511973890.

The spelling of 309809381 in words is "three hundred nine million, eight hundred nine thousand, three hundred eighty-one".