681288509 has 4 divisors (see below), whose sum is σ = 743223840. Its totient is φ = 619353180.

The previous prime is 681288473. The next prime is 681288539. The reversal of 681288509 is 905882186.

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 681288509 - 2⁸ = 681288253 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681288539) 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, 30967649 + ... + 30967670.

It is an arithmetic number, because the mean of its divisors is an integer number (185805960).

Almost surely, 2^681288509 is an apocalyptic number.

It is an amenable number.

681288509 is a deficient number, since it is larger than the sum of its proper divisors (61935331).

681288509 is a wasteful number, since it uses less digits than its factorization.

681288509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 61935330.

The product of its (nonzero) digits is 276480, while the sum is 47.

The square root of 681288509 is about 26101.5039605001. The cubic root of 681288509 is about 879.9210109025.

The spelling of 681288509 in words is "six hundred eighty-one million, two hundred eighty-eight thousand, five hundred nine".