645995941 has 2 divisors, whose sum is σ = 645995942. Its totient is φ = 645995940.

The previous prime is 645995879. The next prime is 645995981. The reversal of 645995941 is 149599546.

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., 611820225 + 34175716 = 24735^2 + 5846^2 .

It is a cyclic number.

It is not a de Polignac number, because 645995941 - 2⁷ = 645995813 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645995981) 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, 322997970 + 322997971.

It is an arithmetic number, because the mean of its divisors is an integer number (322997971).

Almost surely, 2^645995941 is an apocalyptic number.

It is an amenable number.

645995941 is a deficient number, since it is larger than the sum of its proper divisors (1).

645995941 is an equidigital number, since it uses as much as digits as its factorization.

645995941 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1749600, while the sum is 52.

The square root of 645995941 is about 25416.4502045427. The cubic root of 645995941 is about 864.4567366255.

It can be divided in two parts, 6459 and 95941, that added together give a square (102400 = 320²).

The spelling of 645995941 in words is "six hundred forty-five million, nine hundred ninety-five thousand, nine hundred forty-one".