645848521 has 2 divisors, whose sum is σ = 645848522. Its totient is φ = 645848520.

The previous prime is 645848503. The next prime is 645848537. The reversal of 645848521 is 125848546.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 645718921 + 129600 = 25411^2 + 360^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-645848521 is a prime.

It is not a weakly prime, because it can be changed into another prime (645848591) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322924260 + 322924261.

It is an arithmetic number, because the mean of its divisors is an integer number (322924261).

Almost surely, 2^645848521 is an apocalyptic number.

It is an amenable number.

645848521 is a deficient number, since it is larger than the sum of its proper divisors (1).

645848521 is an equidigital number, since it uses as much as digits as its factorization.

645848521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 307200, while the sum is 43.

The square root of 645848521 is about 25413.5499487970. The cubic root of 645848521 is about 864.3909736181.

The spelling of 645848521 in words is "six hundred forty-five million, eight hundred forty-eight thousand, five hundred twenty-one".