640308497 has 2 divisors, whose sum is σ = 640308498. Its totient is φ = 640308496.

The previous prime is 640308467. The next prime is 640308517. The reversal of 640308497 is 794803046.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 528816016 + 111492481 = 22996^2 + 10559^2 .

It is a cyclic number.

It is not a de Polignac number, because 640308497 - 2⁸ = 640308241 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (640308457) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320154248 + 320154249.

It is an arithmetic number, because the mean of its divisors is an integer number (320154249).

Almost surely, 2^640308497 is an apocalyptic number.

It is an amenable number.

640308497 is a deficient number, since it is larger than the sum of its proper divisors (1).

640308497 is an equidigital number, since it uses as much as digits as its factorization.

640308497 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 145152, while the sum is 41.

The square root of 640308497 is about 25304.3177540909. The cubic root of 640308497 is about 861.9123197370.

It can be divided in two parts, 64030 and 8497, that added together give a palindrome (72527).

The spelling of 640308497 in words is "six hundred forty million, three hundred eight thousand, four hundred ninety-seven".