645671757 has 8 divisors (see below), whose sum is σ = 861480576. Its totient is φ = 430155392.

The previous prime is 645671749. The next prime is 645671773. The reversal of 645671757 is 757176546.

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

It is a cyclic number.

It is not a de Polignac number, because 645671757 - 2³ = 645671749 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645671777) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 67908 + ... + 76829.

It is an arithmetic number, because the mean of its divisors is an integer number (107685072).

Almost surely, 2^645671757 is an apocalyptic number.

It is an amenable number.

645671757 is a deficient number, since it is larger than the sum of its proper divisors (215808819).

645671757 is a wasteful number, since it uses less digits than its factorization.

645671757 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 146227.

The product of its digits is 1234800, while the sum is 48.

The square root of 645671757 is about 25410.0719597564. The cubic root of 645671757 is about 864.3121072676.

The spelling of 645671757 in words is "six hundred forty-five million, six hundred seventy-one thousand, seven hundred fifty-seven".