681369391 has 4 divisors (see below), whose sum is σ = 689994400. Its totient is φ = 672744384.

The previous prime is 681369379. The next prime is 681369397. The reversal of 681369391 is 193963186.

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

It is a cyclic number.

It is not a de Polignac number, because 681369391 - 2⁹ = 681368879 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681369397) 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, 4312386 + ... + 4312543.

It is an arithmetic number, because the mean of its divisors is an integer number (172498600).

Almost surely, 2^681369391 is an apocalyptic number.

681369391 is a deficient number, since it is larger than the sum of its proper divisors (8625009).

681369391 is an equidigital number, since it uses as much as digits as its factorization.

681369391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8625008.

The product of its digits is 209952, while the sum is 46.

The square root of 681369391 is about 26103.0532888396. The cubic root of 681369391 is about 879.9558306860.

The spelling of 681369391 in words is "six hundred eighty-one million, three hundred sixty-nine thousand, three hundred ninety-one".