645406273 has 2 divisors, whose sum is σ = 645406274. Its totient is φ = 645406272.

The previous prime is 645406271. The next prime is 645406337. The reversal of 645406273 is 372604546.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 616429584 + 28976689 = 24828^2 + 5383^2 .

It is a cyclic number.

It is not a de Polignac number, because 645406273 - 2¹ = 645406271 is a prime.

Together with 645406271, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (645406271) 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, 322703136 + 322703137.

It is an arithmetic number, because the mean of its divisors is an integer number (322703137).

Almost surely, 2^645406273 is an apocalyptic number.

It is an amenable number.

645406273 is a deficient number, since it is larger than the sum of its proper divisors (1).

645406273 is an equidigital number, since it uses as much as digits as its factorization.

645406273 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 120960, while the sum is 37.

The square root of 645406273 is about 25404.8474311498. The cubic root of 645406273 is about 864.1936298887.

The spelling of 645406273 in words is "six hundred forty-five million, four hundred six thousand, two hundred seventy-three".