681039391 has 4 divisors (see below), whose sum is σ = 681283800. Its totient is φ = 680794984.

The previous prime is 681039383. The next prime is 681039409. The reversal of 681039391 is 193930186.

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 681039391 - 2³ = 681039383 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 (681039311) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 117976 + ... + 123613.

It is an arithmetic number, because the mean of its divisors is an integer number (170320950).

Almost surely, 2^681039391 is an apocalyptic number.

681039391 is a deficient number, since it is larger than the sum of its proper divisors (244409).

681039391 is a wasteful number, since it uses less digits than its factorization.

681039391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 244408.

The product of its (nonzero) digits is 34992, while the sum is 40.

The square root of 681039391 is about 26096.7314236860. The cubic root of 681039391 is about 879.8137480309.

The spelling of 681039391 in words is "six hundred eighty-one million, thirty-nine thousand, three hundred ninety-one".