640722323 has 2 divisors, whose sum is σ = 640722324. Its totient is φ = 640722322.

The previous prime is 640722263. The next prime is 640722343. The reversal of 640722323 is 323227046.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 640722323 - 2¹⁶ = 640656787 is a prime.

It is not a weakly prime, because it can be changed into another prime (640722343) 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, 320361161 + 320361162.

It is an arithmetic number, because the mean of its divisors is an integer number (320361162).

Almost surely, 2^640722323 is an apocalyptic number.

640722323 is a deficient number, since it is larger than the sum of its proper divisors (1).

640722323 is an equidigital number, since it uses as much as digits as its factorization.

640722323 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 12096, while the sum is 29.

The square root of 640722323 is about 25312.4934172831. The cubic root of 640722323 is about 862.0979619791.

Adding to 640722323 its reverse (323227046), we get a palindrome (963949369).

The spelling of 640722323 in words is "six hundred forty million, seven hundred twenty-two thousand, three hundred twenty-three".