645901 has 2 divisors, whose sum is σ = 645902. Its totient is φ = 645900.

The previous prime is 645893. The next prime is 645907. The reversal of 645901 is 109546.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 396900 + 249001 = 630^2 + 499^2 .

It is a cyclic number.

It is not a de Polignac number, because 645901 - 2³ = 645893 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645907) by changing a digit.

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 as a sum of consecutive naturals, namely, 322950 + 322951.

It is an arithmetic number, because the mean of its divisors is an integer number (322951).

2⁶⁴⁵⁹⁰¹ is an apocalyptic number.

It is an amenable number.

645901 is a deficient number, since it is larger than the sum of its proper divisors (1).

645901 is an equidigital number, since it uses as much as digits as its factorization.

645901 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1080, while the sum is 25.

The square root of 645901 is about 803.6796625522. The cubic root of 645901 is about 86.4414385272.

The spelling of 645901 in words is "six hundred forty-five thousand, nine hundred one".