681891764 has 48 divisors (see below), whose sum is σ = 1288011648. Its totient is φ = 315076608.

The previous prime is 681891757. The next prime is 681891781. The reversal of 681891764 is 467198186.

681891764 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×681891764² = 929952755622063392, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 382844 + ... + 384620.

It is an arithmetic number, because the mean of its divisors is an integer number (26833576).

Almost surely, 2^681891764 is an apocalyptic number.

It is an amenable number.

681891764 is a deficient number, since it is larger than the sum of its proper divisors (606119884).

681891764 is a wasteful number, since it uses less digits than its factorization.

681891764 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1944 (or 1942 counting only the distinct ones).

The product of its digits is 580608, while the sum is 50.

The square root of 681891764 is about 26113.0573468524. The cubic root of 681891764 is about 880.1806464543.

The spelling of 681891764 in words is "six hundred eighty-one million, eight hundred ninety-one thousand, seven hundred sixty-four".