640029779 has 2 divisors, whose sum is σ = 640029780. Its totient is φ = 640029778.

The previous prime is 640029773. The next prime is 640029781. The reversal of 640029779 is 977920046.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 640029779 - 2²⁸ = 371594323 is a prime.

Together with 640029781, 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 (640029773) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320014889 + 320014890.

It is an arithmetic number, because the mean of its divisors is an integer number (320014890).

Almost surely, 2^640029779 is an apocalyptic number.

640029779 is a deficient number, since it is larger than the sum of its proper divisors (1).

640029779 is an equidigital number, since it uses as much as digits as its factorization.

640029779 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 190512, while the sum is 44.

The square root of 640029779 is about 25298.8098336661. The cubic root of 640029779 is about 861.7872418285.

The spelling of 640029779 in words is "six hundred forty million, twenty-nine thousand, seven hundred seventy-nine".