640999547 has 2 divisors, whose sum is σ = 640999548. Its totient is φ = 640999546.

The previous prime is 640999531. The next prime is 640999549. The reversal of 640999547 is 745999046.

640999547 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 640999547 - 2⁴ = 640999531 is a prime.

Together with 640999549, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (640999549) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320499773 + 320499774.

It is an arithmetic number, because the mean of its divisors is an integer number (320499774).

Almost surely, 2^640999547 is an apocalyptic number.

640999547 is a deficient number, since it is larger than the sum of its proper divisors (1).

640999547 is an equidigital number, since it uses as much as digits as its factorization.

640999547 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2449440, while the sum is 53.

The square root of 640999547 is about 25317.9688561306. The cubic root of 640999547 is about 862.2222798915. Note that the first 4 decimals are identical.

The spelling of 640999547 in words is "six hundred forty million, nine hundred ninety-nine thousand, five hundred forty-seven".