645554941 has 2 divisors, whose sum is σ = 645554942. Its totient is φ = 645554940.

The previous prime is 645554939. The next prime is 645554971. The reversal of 645554941 is 149455546.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 630763225 + 14791716 = 25115^2 + 3846^2 .

It is a cyclic number.

It is not a de Polignac number, because 645554941 - 2¹ = 645554939 is a prime.

Together with 645554939, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645554971) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322777470 + 322777471.

It is an arithmetic number, because the mean of its divisors is an integer number (322777471).

Almost surely, 2^645554941 is an apocalyptic number.

It is an amenable number.

645554941 is a deficient number, since it is larger than the sum of its proper divisors (1).

645554941 is an equidigital number, since it uses as much as digits as its factorization.

645554941 is an evil number, because the sum of its binary digits is even.

The product of its digits is 432000, while the sum is 43.

The square root of 645554941 is about 25407.7732396997. The cubic root of 645554941 is about 864.2599798661.

It can be divided in two parts, 64555 and 4941, that added together give a palindrome (69496).

The spelling of 645554941 in words is "six hundred forty-five million, five hundred fifty-four thousand, nine hundred forty-one".