680645877781 has 4 divisors (see below), whose sum is σ = 680943495232. Its totient is φ = 680348260332.

The previous prime is 680645877739. The next prime is 680645877817. The reversal of 680645877781 is 187778546086.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 680645877781 - 2¹¹ = 680645875733 is a prime.

It is a super-2 number, since 2×680645877781² (a number of 24 digits) 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 (680645877881) 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, 148805295 + ... + 148809868.

It is an arithmetic number, because the mean of its divisors is an integer number (170235873808).

Almost surely, 2^680645877781 is an apocalyptic number.

It is an amenable number.

680645877781 is a deficient number, since it is larger than the sum of its proper divisors (297617451).

680645877781 is a wasteful number, since it uses less digits than its factorization.

680645877781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 297617450.

The product of its (nonzero) digits is 126443520, while the sum is 67.

The spelling of 680645877781 in words is "six hundred eighty billion, six hundred forty-five million, eight hundred seventy-seven thousand, seven hundred eighty-one".