640445929 has 2 divisors, whose sum is σ = 640445930. Its totient is φ = 640445928.

The previous prime is 640445909. The next prime is 640446013. The reversal of 640445929 is 929544046.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 458816400 + 181629529 = 21420^2 + 13477^2 .

It is a cyclic number.

It is not a de Polignac number, because 640445929 - 2⁷ = 640445801 is a prime.

It is not a weakly prime, because it can be changed into another prime (640445909) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320222964 + 320222965.

It is an arithmetic number, because the mean of its divisors is an integer number (320222965).

Almost surely, 2^640445929 is an apocalyptic number.

It is an amenable number.

640445929 is a deficient number, since it is larger than the sum of its proper divisors (1).

640445929 is an equidigital number, since it uses as much as digits as its factorization.

640445929 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 311040, while the sum is 43.

The square root of 640445929 is about 25307.0331923756. The cubic root of 640445929 is about 861.9739805670.

The spelling of 640445929 in words is "six hundred forty million, four hundred forty-five thousand, nine hundred twenty-nine".