640356523 has 2 divisors, whose sum is σ = 640356524. Its totient is φ = 640356522.

The previous prime is 640356413. The next prime is 640356533. The reversal of 640356523 is 325653046.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 640356523 - 2¹⁷ = 640225451 is a prime.

It is not a weakly prime, because it can be changed into another prime (640356533) 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, 320178261 + 320178262.

It is an arithmetic number, because the mean of its divisors is an integer number (320178262).

Almost surely, 2^640356523 is an apocalyptic number.

640356523 is a deficient number, since it is larger than the sum of its proper divisors (1).

640356523 is an equidigital number, since it uses as much as digits as its factorization.

640356523 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 64800, while the sum is 34.

The square root of 640356523 is about 25305.2667047791. The cubic root of 640356523 is about 861.9338682907.

It can be divided in two parts, 6403 and 56523, that added together give a palindrome (62926).

The spelling of 640356523 in words is "six hundred forty million, three hundred fifty-six thousand, five hundred twenty-three".