645989815 has 8 divisors (see below), whose sum is σ = 775633248. Its totient is φ = 516494880.

The previous prime is 645989791. The next prime is 645989831. The reversal of 645989815 is 518989546.

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

It is not a de Polignac number, because 645989815 - 2¹¹ = 645987767 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 27316 + ... + 45145.

It is an arithmetic number, because the mean of its divisors is an integer number (96954156).

Almost surely, 2^645989815 is an apocalyptic number.

645989815 is a deficient number, since it is larger than the sum of its proper divisors (129643433).

645989815 is a wasteful number, since it uses less digits than its factorization.

645989815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 74249.

The product of its digits is 3110400, while the sum is 55.

The square root of 645989815 is about 25416.3296917553. The cubic root of 645989815 is about 864.4540040599.

The spelling of 645989815 in words is "six hundred forty-five million, nine hundred eighty-nine thousand, eight hundred fifteen".