645347993 has 2 divisors, whose sum is σ = 645347994. Its totient is φ = 645347992.

The previous prime is 645347957. The next prime is 645348001. The reversal of 645347993 is 399743546.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 644550544 + 797449 = 25388^2 + 893^2 .

It is a cyclic number.

It is not a de Polignac number, because 645347993 - 2²⁰ = 644299417 is a prime.

It is not a weakly prime, because it can be changed into another prime (645341993) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322673996 + 322673997.

It is an arithmetic number, because the mean of its divisors is an integer number (322673997).

Almost surely, 2^645347993 is an apocalyptic number.

It is an amenable number.

645347993 is a deficient number, since it is larger than the sum of its proper divisors (1).

645347993 is an equidigital number, since it uses as much as digits as its factorization.

645347993 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2449440, while the sum is 50.

The square root of 645347993 is about 25403.7003800627. The cubic root of 645347993 is about 864.1676169606.

It can be divided in two parts, 64534 and 7993, that added together give a palindrome (72527).

The spelling of 645347993 in words is "six hundred forty-five million, three hundred forty-seven thousand, nine hundred ninety-three".