645244020 has 36 divisors (see below), whose sum is σ = 1957240740. Its totient is φ = 172065024.

The previous prime is 645244003. The next prime is 645244049. The reversal of 645244020 is 20442546.

645244020 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 293231376 + 352012644 = 17124^2 + 18762^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1792165 + ... + 1792524.

Almost surely, 2^645244020 is an apocalyptic number.

645244020 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

645244020 is an abundant number, since it is smaller than the sum of its proper divisors (1311996720).

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

645244020 is a wasteful number, since it uses less digits than its factorization.

645244020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3584704 (or 3584699 counting only the distinct ones).

The product of its (nonzero) digits is 7680, while the sum is 27.

The square root of 645244020 is about 25401.6538831628. The cubic root of 645244020 is about 864.1212053469.

Adding to 645244020 its reverse (20442546), we get a palindrome (665686566).

The spelling of 645244020 in words is "six hundred forty-five million, two hundred forty-four thousand, twenty".