640446067 has 2 divisors, whose sum is σ = 640446068. Its totient is φ = 640446066.

The previous prime is 640446043. The next prime is 640446073. The reversal of 640446067 is 760644046.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-640446067 is a prime.

It is not a weakly prime, because it can be changed into another prime (640446077) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320223033 + 320223034.

It is an arithmetic number, because the mean of its divisors is an integer number (320223034).

Almost surely, 2^640446067 is an apocalyptic number.

640446067 is a deficient number, since it is larger than the sum of its proper divisors (1).

640446067 is an equidigital number, since it uses as much as digits as its factorization.

640446067 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 96768, while the sum is 37.

The square root of 640446067 is about 25307.0359188902. The cubic root of 640446067 is about 861.9740424782.

The spelling of 640446067 in words is "six hundred forty million, four hundred forty-six thousand, sixty-seven".