681045509 has 4 divisors (see below), whose sum is σ = 681102816. Its totient is φ = 680988204.

The previous prime is 681045503. The next prime is 681045511. The reversal of 681045509 is 905540186.

681045509 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 681045509 - 2¹⁶ = 680979973 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 (681045503) 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, 3419 + ... + 37064.

It is an arithmetic number, because the mean of its divisors is an integer number (170275704).

Almost surely, 2^681045509 is an apocalyptic number.

It is an amenable number.

681045509 is a deficient number, since it is larger than the sum of its proper divisors (57307).

681045509 is a wasteful number, since it uses less digits than its factorization.

681045509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57306.

The product of its (nonzero) digits is 43200, while the sum is 38.

The square root of 681045509 is about 26096.8486411674. The cubic root of 681045509 is about 879.8163825747.

The spelling of 681045509 in words is "six hundred eighty-one million, forty-five thousand, five hundred nine".