645738493 has 2 divisors, whose sum is σ = 645738494.
Its totient is φ = 645738492.
The previous prime is 645738487. The next prime is 645738517. The reversal of 645738493 is 394837546.
It is a weak prime.
It can be written as a sum of positive squares in only one way, i.e., 625650169 + 20088324 = 25013^2 + 4482^2
It is a cyclic number.
It is not a de Polignac number, because 645738493 - 25 = 645738461 is a prime.
It is a super-2 number, since 2×6457384932 = 833956402683822098, which contains 22 as substring.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (645738433) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322869246 + 322869247.
It is an arithmetic number, because the mean of its divisors is an integer number (322869247).
Almost surely, 2645738493 is an apocalyptic number.
It is an amenable number.
645738493 is a deficient number, since it is larger than the sum of its proper divisors (1).
645738493 is an equidigital number, since it uses as much as digits as its factorization.
645738493 is an odious number, because the sum of its binary digits is odd.
The product of its digits is 2177280, while the sum is 49.
The square root of 645738493 is about 25411.3851058930.
The cubic root of 645738493 is about 864.3418843925.
The spelling of 645738493 in words is "six hundred forty-five million, seven hundred thirty-eight thousand, four hundred ninety-three".