391343681 has 4 divisors (see below), whose sum is σ = 394934100. Its totient is φ = 387753264.

The previous prime is 391343671. The next prime is 391343683. The reversal of 391343681 is 186343193.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 250114225 + 141229456 = 15815^2 + 11884^2 .

It is a cyclic number.

It is not a de Polignac number, because 391343681 - 2¹⁰ = 391342657 is a prime.

It is a super-2 number, since 2×391343681² = 306299753317259522, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (391343683) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1795046 + ... + 1795263.

It is an arithmetic number, because the mean of its divisors is an integer number (98733525).

Almost surely, 2^391343681 is an apocalyptic number.

It is an amenable number.

391343681 is a deficient number, since it is larger than the sum of its proper divisors (3590419).

391343681 is a wasteful number, since it uses less digits than its factorization.

391343681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3590418.

The product of its digits is 46656, while the sum is 38.

The square root of 391343681 is about 19782.4083720865. The cubic root of 391343681 is about 731.4524662440.

The spelling of 391343681 in words is "three hundred ninety-one million, three hundred forty-three thousand, six hundred eighty-one".