645171738 has 16 divisors (see below), whose sum is σ = 1325218080. Its totient is φ = 209244816.

The previous prime is 645171719. The next prime is 645171757. The reversal of 645171738 is 837171546.

It is an interprime number because it is at equal distance from previous prime (645171719) and next prime (645171757).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 645171738.

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 7 ways as a sum of consecutive naturals, for example, 1452868 + ... + 1453311.

It is an arithmetic number, because the mean of its divisors is an integer number (82826130).

Almost surely, 2^645171738 is an apocalyptic number.

645171738 is an abundant number, since it is smaller than the sum of its proper divisors (680046342).

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

645171738 is a wasteful number, since it uses less digits than its factorization.

645171738 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2906221.

The product of its digits is 141120, while the sum is 42.

The square root of 645171738 is about 25400.2310619411. The cubic root of 645171738 is about 864.0889370682.

The spelling of 645171738 in words is "six hundred forty-five million, one hundred seventy-one thousand, seven hundred thirty-eight".