646207745 has 4 divisors (see below), whose sum is σ = 775449300. Its totient is φ = 516966192.

The previous prime is 646207733. The next prime is 646207759. The reversal of 646207745 is 547702646.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 547702646 = 2 ⋅273851323.

It can be written as a sum of positive squares in 2 ways, for example, as 493017616 + 153190129 = 22204^2 + 12377^2 .

It is a cyclic number.

It is not a de Polignac number, because 646207745 - 2¹⁰ = 646206721 is a prime.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64620770 + ... + 64620779.

It is an arithmetic number, because the mean of its divisors is an integer number (193862325).

Almost surely, 2^646207745 is an apocalyptic number.

It is an amenable number.

646207745 is a deficient number, since it is larger than the sum of its proper divisors (129241555).

646207745 is a wasteful number, since it uses less digits than its factorization.

646207745 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 129241554.

The product of its (nonzero) digits is 282240, while the sum is 41.

The square root of 646207745 is about 25420.6165346162. The cubic root of 646207745 is about 864.5512033633.

The spelling of 646207745 in words is "six hundred forty-six million, two hundred seven thousand, seven hundred forty-five".