645727553 has 6 divisors (see below), whose sum is σ = 675023874. Its totient is φ = 617651936.

The previous prime is 645727549. The next prime is 645727561. The reversal of 645727553 is 355727546.

It can be written as a sum of positive squares in only one way, i.e., 418079809 + 227647744 = 20447^2 + 15088^2 .

It is not a de Polignac number, because 645727553 - 2² = 645727549 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645727853) by changing a digit.

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 5 ways as a sum of consecutive naturals, for example, 609800 + ... + 610857.

It is an arithmetic number, because the mean of its divisors is an integer number (112503979).

Almost surely, 2^645727553 is an apocalyptic number.

It is an amenable number.

645727553 is a deficient number, since it is larger than the sum of its proper divisors (29296321).

645727553 is a wasteful number, since it uses less digits than its factorization.

645727553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1220703 (or 1220680 counting only the distinct ones).

The product of its digits is 882000, while the sum is 44.

The square root of 645727553 is about 25411.1698471361. The cubic root of 645727553 is about 864.3370031835.

The spelling of 645727553 in words is "six hundred forty-five million, seven hundred twenty-seven thousand, five hundred fifty-three".