645443531665 has 8 divisors (see below), whose sum is σ = 782051969088. Its totient is φ = 511341671280.

The previous prime is 645443531633. The next prime is 645443531687. The reversal of 645443531665 is 566135344546.

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

It is not a de Polignac number, because 645443531665 - 2⁵ = 645443531633 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 626643691 + ... + 626644720.

It is an arithmetic number, because the mean of its divisors is an integer number (97756496136).

Almost surely, 2^645443531665 is an apocalyptic number.

It is an amenable number.

645443531665 is a deficient number, since it is larger than the sum of its proper divisors (136608437423).

645443531665 is a wasteful number, since it uses less digits than its factorization.

645443531665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1253288519.

The product of its digits is 15552000, while the sum is 52.

The spelling of 645443531665 in words is "six hundred forty-five billion, four hundred forty-three million, five hundred thirty-one thousand, six hundred sixty-five".