681520638 has 8 divisors (see below), whose sum is σ = 1363041288. Its totient is φ = 227173544.

The previous prime is 681520603. The next prime is 681520643. The reversal of 681520638 is 836025186.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

681520638 is an admirable number.

It is a junction number, because it is equal to n+sod(n) for n = 681520596 and 681520605.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 56793381 + ... + 56793392.

It is an arithmetic number, because the mean of its divisors is an integer number (170380161).

Almost surely, 2^681520638 is an apocalyptic number.

681520638 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

681520638 is a wasteful number, since it uses less digits than its factorization.

681520638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 113586778.

The product of its (nonzero) digits is 69120, while the sum is 39.

The square root of 681520638 is about 26105.9502412764. The cubic root of 681520638 is about 880.0209352802.

The spelling of 681520638 in words is "six hundred eighty-one million, five hundred twenty thousand, six hundred thirty-eight".