645563639 has 4 divisors (see below), whose sum is σ = 737787024. Its totient is φ = 553340256.

The previous prime is 645563621. The next prime is 645563647. The reversal of 645563639 is 936365546.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 645563639 - 2¹² = 645559543 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 645563593 and 645563602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645563239) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 46111682 + ... + 46111695.

It is an arithmetic number, because the mean of its divisors is an integer number (184446756).

Almost surely, 2^645563639 is an apocalyptic number.

645563639 is a deficient number, since it is larger than the sum of its proper divisors (92223385).

645563639 is an equidigital number, since it uses as much as digits as its factorization.

645563639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 92223384.

The product of its digits is 1749600, while the sum is 47.

The square root of 645563639 is about 25407.9444072125. The cubic root of 645563639 is about 864.2638614358.

The spelling of 645563639 in words is "six hundred forty-five million, five hundred sixty-three thousand, six hundred thirty-nine".