645955 has 16 divisors (see below), whose sum is σ = 834624. Its totient is φ = 478720.

The previous prime is 645941. The next prime is 645973. The reversal of 645955 is 559546.

It is a happy number.

It is not a de Polignac number, because 645955 - 2⁹ = 645443 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 645955.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4647 + ... + 4783.

It is an arithmetic number, because the mean of its divisors is an integer number (52164).

2⁶⁴⁵⁹⁵⁵ is an apocalyptic number.

645955 is a deficient number, since it is larger than the sum of its proper divisors (188669).

645955 is a wasteful number, since it uses less digits than its factorization.

645955 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 206.

The product of its digits is 27000, while the sum is 34.

The square root of 645955 is about 803.7132573250. The cubic root of 645955 is about 86.4438474142.

It can be divided in two parts, 645 and 955, that added together give a square (1600 = 40²).

The spelling of 645955 in words is "six hundred forty-five thousand, nine hundred fifty-five".