643651145 has 4 divisors (see below), whose sum is σ = 772381380. Its totient is φ = 514920912.

The previous prime is 643651121. The next prime is 643651181. The reversal of 643651145 is 541156346.

643651145 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 541156346 = 2 ⋅270578173.

It can be written as a sum of positive squares in 2 ways, for example, as 491597584 + 152053561 = 22172^2 + 12331^2 .

It is a cyclic number.

It is not a de Polignac number, because 643651145 - 2⁶ = 643651081 is a prime.

It is a super-2 number, since 2×643651145² = 828573592919622050, which contains 22 as substring.

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, 64365110 + ... + 64365119.

It is an arithmetic number, because the mean of its divisors is an integer number (193095345).

Almost surely, 2^643651145 is an apocalyptic number.

It is an amenable number.

643651145 is a deficient number, since it is larger than the sum of its proper divisors (128730235).

643651145 is a wasteful number, since it uses less digits than its factorization.

643651145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128730234.

The product of its digits is 43200, while the sum is 35.

The square root of 643651145 is about 25370.2807434210. The cubic root of 643651145 is about 863.4095514502.

The spelling of 643651145 in words is "six hundred forty-three million, six hundred fifty-one thousand, one hundred forty-five".