645503620 has 24 divisors (see below), whose sum is σ = 1358242200. Its totient is φ = 257690112.

The previous prime is 645503609. The next prime is 645503633. The reversal of 645503620 is 26305546.

It can be written as a sum of positive squares in 4 ways, for example, as 33732864 + 611770756 = 5808^2 + 24734^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21525 + ... + 41884.

It is an arithmetic number, because the mean of its divisors is an integer number (56593425).

Almost surely, 2^645503620 is an apocalyptic number.

It is an amenable number.

645503620 is an abundant number, since it is smaller than the sum of its proper divisors (712738580).

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

645503620 is a wasteful number, since it uses less digits than its factorization.

645503620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63927 (or 63925 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 31.

The square root of 645503620 is about 25406.7632727981. The cubic root of 645503620 is about 864.2370766454.

The spelling of 645503620 in words is "six hundred forty-five million, five hundred three thousand, six hundred twenty".