645818815 has 16 divisors (see below), whose sum is σ = 800789760. Its totient is φ = 499484160.

The previous prime is 645818801. The next prime is 645818819. The reversal of 645818815 is 518818546.

It is not a de Polignac number, because 645818815 - 2¹⁹ = 645294527 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645818819) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 246231 + ... + 248839.

It is an arithmetic number, because the mean of its divisors is an integer number (50049360).

Almost surely, 2^645818815 is an apocalyptic number.

645818815 is a deficient number, since it is larger than the sum of its proper divisors (154970945).

645818815 is a wasteful number, since it uses less digits than its factorization.

645818815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4242.

The product of its digits is 307200, while the sum is 46.

The square root of 645818815 is about 25412.9654900801. The cubic root of 645818815 is about 864.3777207727.

The spelling of 645818815 in words is "six hundred forty-five million, eight hundred eighteen thousand, eight hundred fifteen".