1368391681 has 4 divisors (see below), whose sum is σ = 1372708692. Its totient is φ = 1364074672.

The previous prime is 1368391679. The next prime is 1368391691. The reversal of 1368391681 is 1861938631.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1861938631 = 7 ⋅265991233.

It can be written as a sum of positive squares in 2 ways, for example, as 80730225 + 1287661456 = 8985^2 + 35884^2 .

It is a cyclic number.

It is not a de Polignac number, because 1368391681 - 2¹ = 1368391679 is a prime.

It is a super-2 number, since 2×1368391681² = 3744991585260011522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1368391691) 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, 2158030 + ... + 2158663.

It is an arithmetic number, because the mean of its divisors is an integer number (343177173).

It is a Proth number, since it is equal to 1305 ⋅ 2²⁰ + 1 and 1305 < 2²⁰.

Almost surely, 2^1368391681 is an apocalyptic number.

It is an amenable number.

1368391681 is a deficient number, since it is larger than the sum of its proper divisors (4317011).

1368391681 is an equidigital number, since it uses as much as digits as its factorization.

1368391681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4317010.

The product of its digits is 186624, while the sum is 46.

The square root of 1368391681 is about 36991.7785595664. The cubic root of 1368391681 is about 1110.2057571118.

The spelling of 1368391681 in words is "one billion, three hundred sixty-eight million, three hundred ninety-one thousand, six hundred eighty-one".