645344665765 has 16 divisors (see below), whose sum is σ = 774930252096. Its totient is φ = 515931436800.

The previous prime is 645344665717. The next prime is 645344665789. The reversal of 645344665765 is 567566443546.

It is not a de Polignac number, because 645344665765 - 2¹⁵ = 645344632997 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 62461650 + ... + 62471980.

It is an arithmetic number, because the mean of its divisors is an integer number (48433140756).

Almost surely, 2^645344665765 is an apocalyptic number.

It is an amenable number.

645344665765 is a deficient number, since it is larger than the sum of its proper divisors (129585586331).

645344665765 is a wasteful number, since it uses less digits than its factorization.

645344665765 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17460.

The product of its digits is 217728000, while the sum is 61.

The spelling of 645344665765 in words is "six hundred forty-five billion, three hundred forty-four million, six hundred sixty-five thousand, seven hundred sixty-five".