645751 has 2 divisors, whose sum is σ = 645752. Its totient is φ = 645750.

The previous prime is 645739. The next prime is 645763. The reversal of 645751 is 157546.

It is a balanced prime because it is at equal distance from previous prime (645739) and next prime (645763).

It is a cyclic number.

It is not a de Polignac number, because 645751 - 2¹¹ = 643703 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645851) 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 as a sum of consecutive naturals, namely, 322875 + 322876.

It is an arithmetic number, because the mean of its divisors is an integer number (322876).

2⁶⁴⁵⁷⁵¹ is an apocalyptic number.

645751 is a deficient number, since it is larger than the sum of its proper divisors (1).

645751 is an equidigital number, since it uses as much as digits as its factorization.

645751 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4200, while the sum is 28.

The square root of 645751 is about 803.5863363697. The cubic root of 645751 is about 86.4347464698.

The spelling of 645751 in words is "six hundred forty-five thousand, seven hundred fifty-one".