645641 has 2 divisors, whose sum is σ = 645642. Its totient is φ = 645640.

The previous prime is 645629. The next prime is 645647. The reversal of 645641 is 146546.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 395641 + 250000 = 629^2 + 500^2 .

It is a cyclic number.

It is not a de Polignac number, because 645641 - 2⁶ = 645577 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 645641.

It is not a weakly prime, because it can be changed into another prime (645647) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322820 + 322821.

It is an arithmetic number, because the mean of its divisors is an integer number (322821).

2⁶⁴⁵⁶⁴¹ is an apocalyptic number.

It is an amenable number.

645641 is a deficient number, since it is larger than the sum of its proper divisors (1).

645641 is an equidigital number, since it uses as much as digits as its factorization.

645641 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2880, while the sum is 26.

The square root of 645641 is about 803.5178902800. The cubic root of 645641 is about 86.4298383024.

The spelling of 645641 in words is "six hundred forty-five thousand, six hundred forty-one".