681781639 has 36 divisors (see below), whose sum is σ = 886977000. Its totient is φ = 521986080.

The previous prime is 681781631. The next prime is 681781657. The reversal of 681781639 is 936187186.

It is not a de Polignac number, because 681781639 - 2³ = 681781631 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (49).

It is a junction number, because it is equal to n+sod(n) for n = 681781592 and 681781601.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681781631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 348837 + ... + 350785.

It is an arithmetic number, because the mean of its divisors is an integer number (24638250).

Almost surely, 2^681781639 is an apocalyptic number.

681781639 is a deficient number, since it is larger than the sum of its proper divisors (205195361).

681781639 is a wasteful number, since it uses less digits than its factorization.

681781639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2044 (or 2026 counting only the distinct ones).

The product of its digits is 435456, while the sum is 49.

The square root of 681781639 is about 26110.9486422841. The cubic root of 681781639 is about 880.1332610689.

The spelling of 681781639 in words is "six hundred eighty-one million, seven hundred eighty-one thousand, six hundred thirty-nine".