645205320 has 48 divisors (see below), whose sum is σ = 2096918460. Its totient is φ = 172054656.

The previous prime is 645205291. The next prime is 645205343. The reversal of 645205320 is 23502546.

It can be written as a sum of positive squares in 2 ways, for example, as 628705476 + 16499844 = 25074^2 + 4062^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 895759 + ... + 896478.

Almost surely, 2^645205320 is an apocalyptic number.

645205320 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

645205320 is an abundant number, since it is smaller than the sum of its proper divisors (1451713140).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

645205320 is a wasteful number, since it uses less digits than its factorization.

645205320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1792254 (or 1792247 counting only the distinct ones).

The product of its (nonzero) digits is 7200, while the sum is 27.

The square root of 645205320 is about 25400.8921103177. The cubic root of 645205320 is about 864.1039291133.

Adding to 645205320 its reverse (23502546), we get a palindrome (668707866).

The spelling of 645205320 in words is "six hundred forty-five million, two hundred five thousand, three hundred twenty".