645440693 has 2 divisors, whose sum is σ = 645440694. Its totient is φ = 645440692.

The previous prime is 645440689. The next prime is 645440701. The reversal of 645440693 is 396044546.

645440693 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 620109604 + 25331089 = 24902^2 + 5033^2 .

It is a cyclic number.

It is not a de Polignac number, because 645440693 - 2² = 645440689 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 645440693.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645440633) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322720346 + 322720347.

It is an arithmetic number, because the mean of its divisors is an integer number (322720347).

Almost surely, 2^645440693 is an apocalyptic number.

It is an amenable number.

645440693 is a deficient number, since it is larger than the sum of its proper divisors (1).

645440693 is an equidigital number, since it uses as much as digits as its factorization.

645440693 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 311040, while the sum is 41.

The square root of 645440693 is about 25405.5248518900. The cubic root of 645440693 is about 864.2089923134.

The spelling of 645440693 in words is "six hundred forty-five million, four hundred forty thousand, six hundred ninety-three".