681508643 has 4 divisors (see below), whose sum is σ = 682632000. Its totient is φ = 680385288.

The previous prime is 681508637. The next prime is 681508649. The reversal of 681508643 is 346805186.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (681508637) and next prime (681508649).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-681508643 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 681508643.

It is not an unprimeable number, because it can be changed into a prime (681508649) 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, 560768 + ... + 561981.

It is an arithmetic number, because the mean of its divisors is an integer number (170658000).

Almost surely, 2^681508643 is an apocalyptic number.

681508643 is a deficient number, since it is larger than the sum of its proper divisors (1123357).

681508643 is a wasteful number, since it uses less digits than its factorization.

681508643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1123356.

The product of its (nonzero) digits is 138240, while the sum is 41.

The square root of 681508643 is about 26105.7205033686. The cubic root of 681508643 is about 880.0157723585.

The spelling of 681508643 in words is "six hundred eighty-one million, five hundred eight thousand, six hundred forty-three".