645939505 has 4 divisors (see below), whose sum is σ = 775127412. Its totient is φ = 516751600.

The previous prime is 645939487. The next prime is 645939571. The reversal of 645939505 is 505939546.

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 313679521 + 332259984 = 17711^2 + 18228^2 .

It is not a de Polignac number, because 645939505 - 2¹³ = 645931313 is a prime.

It is a Duffinian 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, 64593946 + ... + 64593955.

It is an arithmetic number, because the mean of its divisors is an integer number (193781853).

Almost surely, 2^645939505 is an apocalyptic number.

It is an amenable number.

645939505 is a deficient number, since it is larger than the sum of its proper divisors (129187907).

645939505 is a wasteful number, since it uses less digits than its factorization.

645939505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 129187906.

The product of its (nonzero) digits is 729000, while the sum is 46.

The square root of 645939505 is about 25415.3399544448. The cubic root of 645939505 is about 864.4315621117.

The spelling of 645939505 in words is "six hundred forty-five million, nine hundred thirty-nine thousand, five hundred five".