640749523 has 2 divisors, whose sum is σ = 640749524. Its totient is φ = 640749522.

The previous prime is 640749463. The next prime is 640749569. The reversal of 640749523 is 325947046.

It is a happy number.

640749523 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 640749523 - 2²⁵ = 607195091 is a prime.

It is not a weakly prime, because it can be changed into another prime (640749623) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320374761 + 320374762.

It is an arithmetic number, because the mean of its divisors is an integer number (320374762).

Almost surely, 2^640749523 is an apocalyptic number.

640749523 is a deficient number, since it is larger than the sum of its proper divisors (1).

640749523 is an equidigital number, since it uses as much as digits as its factorization.

640749523 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 181440, while the sum is 40.

The square root of 640749523 is about 25313.0306956714. The cubic root of 640749523 is about 862.1101610925.

The spelling of 640749523 in words is "six hundred forty million, seven hundred forty-nine thousand, five hundred twenty-three".