645559073 has 4 divisors (see below), whose sum is σ = 647169348. Its totient is φ = 643948800.

The previous prime is 645559069. The next prime is 645559081. The reversal of 645559073 is 370955546.

645559073 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.

It can be written as a sum of positive squares in 2 ways, for example, as 548871184 + 96687889 = 23428^2 + 9833^2 .

It is a cyclic number.

It is not a de Polignac number, because 645559073 - 2² = 645559069 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645559093) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 804536 + ... + 805337.

It is an arithmetic number, because the mean of its divisors is an integer number (161792337).

Almost surely, 2^645559073 is an apocalyptic number.

It is an amenable number.

645559073 is a deficient number, since it is larger than the sum of its proper divisors (1610275).

645559073 is a wasteful number, since it uses less digits than its factorization.

645559073 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1610274.

The product of its (nonzero) digits is 567000, while the sum is 44.

The square root of 645559073 is about 25407.8545532676. The cubic root of 645559073 is about 864.2618238169.

The spelling of 645559073 in words is "six hundred forty-five million, five hundred fifty-nine thousand, seventy-three".