645173057 has 4 divisors (see below), whose sum is σ = 647683716. Its totient is φ = 642662400.

The previous prime is 645173041. The next prime is 645173077. The reversal of 645173057 is 750371546.

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

It can be written as a sum of positive squares in 2 ways, for example, as 469848976 + 175324081 = 21676^2 + 13241^2 .

It is a cyclic number.

It is not a de Polignac number, because 645173057 - 2⁴ = 645173041 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 645173057.

It is not an unprimeable number, because it can be changed into a prime (645173017) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1254944 + ... + 1255457.

It is an arithmetic number, because the mean of its divisors is an integer number (161920929).

Almost surely, 2^645173057 is an apocalyptic number.

It is an amenable number.

645173057 is a deficient number, since it is larger than the sum of its proper divisors (2510659).

645173057 is a wasteful number, since it uses less digits than its factorization.

645173057 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2510658.

The product of its (nonzero) digits is 88200, while the sum is 38.

The square root of 645173057 is about 25400.2570262586. The cubic root of 645173057 is about 864.0895259205.

The spelling of 645173057 in words is "six hundred forty-five million, one hundred seventy-three thousand, fifty-seven".